diff --git a/src/fs.cpp b/src/fs.cpp
index 31a2a521..91d66e0c 100644
--- a/src/fs.cpp
+++ b/src/fs.cpp
@@ -151,7 +151,7 @@ namespace fs
       return -1;
 
     dev = st.st_dev;
-    for(int i = 0, ei = srcmounts.size(); i != ei; i++)
+    for(size_t i = 0, ei = srcmounts.size(); i != ei; i++)
       {
         fs::path::make(&srcmounts[i],fusepath,fullpath);
 
@@ -241,7 +241,7 @@ namespace fs
         if(spaceavail <= mfs)
           continue;
 
-        mfs         = spaceavail;
+        mfs         = (fsblkcnt_t)spaceavail;
         mfsbasepath = &basepaths[i];
       }
 
diff --git a/src/fs_acl.cpp b/src/fs_acl.cpp
index 65b40bb2..d30ceecf 100644
--- a/src/fs_acl.cpp
+++ b/src/fs_acl.cpp
@@ -30,7 +30,7 @@ namespace fs
     bool
     dir_has_defaults(const std::string &fullpath)
     {
-      int rv;
+      ssize_t rv;
       std::string dirpath = fullpath;
 
       fs::path::dirname(dirpath);
diff --git a/src/fs_base_getxattr.hpp b/src/fs_base_getxattr.hpp
index eb3deb17..b0ec163b 100644
--- a/src/fs_base_getxattr.hpp
+++ b/src/fs_base_getxattr.hpp
@@ -28,7 +28,7 @@ namespace fs
 {
   static
   inline
-  int
+  ssize_t
   lgetxattr(const std::string &path,
             const char        *attrname,
             void              *value,
diff --git a/src/fs_base_ioctl.hpp b/src/fs_base_ioctl.hpp
index 9de63983..980378b6 100644
--- a/src/fs_base_ioctl.hpp
+++ b/src/fs_base_ioctl.hpp
@@ -26,9 +26,9 @@ namespace fs
   static
   inline
   int
-  ioctl(const int  fd,
-        const int  request,
-        void      *data)
+  ioctl(const int            fd,
+        const unsigned long  request,
+        void                *data)
   {
     return ::ioctl(fd,request,data);
   }
diff --git a/src/fs_base_listxattr.hpp b/src/fs_base_listxattr.hpp
index 4e651679..1ce6020d 100644
--- a/src/fs_base_listxattr.hpp
+++ b/src/fs_base_listxattr.hpp
@@ -28,7 +28,7 @@ namespace fs
 {
   static
   inline
-  int
+  ssize_t
   llistxattr(const std::string &path,
              char              *list,
              const size_t       size)
diff --git a/src/fs_base_readlink.hpp b/src/fs_base_readlink.hpp
index efe7fa47..b0c6cb92 100644
--- a/src/fs_base_readlink.hpp
+++ b/src/fs_base_readlink.hpp
@@ -27,7 +27,7 @@ namespace fs
 {
   static
   inline
-  int
+  ssize_t
   readlink(const std::string &path,
            char              *buf,
            const size_t       bufsiz)
diff --git a/src/fs_clonefile.cpp b/src/fs_clonefile.cpp
index 826790b9..0def2166 100644
--- a/src/fs_clonefile.cpp
+++ b/src/fs_clonefile.cpp
@@ -48,13 +48,13 @@
 using std::string;
 using std::vector;
 
-int
+ssize_t
 writen(const int     fd,
        const char   *buf,
        const size_t  count)
 {
   size_t nleft;
-  ssize_t nwritten;
+  ssize_t nwritten = 0;
 
   nleft = count;
   while(nleft > 0)
@@ -67,15 +67,15 @@ writen(const int     fd,
           return -1;
         }
 
-      nleft -= nwritten;
-      buf   += nwritten;
+      nleft -= (size_t)nwritten;
+      buf   += (size_t)nwritten;
     }
 
-  return count;
+  return nwritten;
 }
 
 static
-int
+ssize_t
 copyfile_rw(const int    fdin,
             const int    fdout,
             const size_t count,
@@ -83,8 +83,8 @@ copyfile_rw(const int    fdin,
 {
   ssize_t nr;
   ssize_t nw;
-  ssize_t bufsize;
-  size_t  totalwritten;
+  size_t  bufsize;
+  ssize_t totalwritten;
   vector<char> buf;
 
   bufsize = (blocksize * 16);
@@ -93,7 +93,7 @@ copyfile_rw(const int    fdin,
   fs::lseek(fdin,0,SEEK_SET);
 
   totalwritten = 0;
-  while(totalwritten < count)
+  while(totalwritten < (ssize_t)count)
     {
       nr = fs::read(fdin,&buf[0],bufsize);
       if(nr == -1)
@@ -103,29 +103,30 @@ copyfile_rw(const int    fdin,
           return -1;
         }
 
-      nw = writen(fdout,&buf[0],nr);
+      nw = writen(fdout,&buf[0],(size_t)nr);
       if(nw == -1)
         return -1;
 
       totalwritten += nw;
     }
 
-  return count;
+  return totalwritten;
 }
 
 static
-int
+ssize_t
 copydata(const int    fdin,
          const int    fdout,
          const size_t count,
          const size_t blocksize)
 {
-  int rv;
+  ssize_t rv;
+  off_t scount = (off_t)count;
+	
+  fs::fadvise(fdin,0,scount,POSIX_FADV_WILLNEED);
+  fs::fadvise(fdin,0,scount,POSIX_FADV_SEQUENTIAL);
 
-  fs::fadvise(fdin,0,count,POSIX_FADV_WILLNEED);
-  fs::fadvise(fdin,0,count,POSIX_FADV_SEQUENTIAL);
-
-  fs::fallocate(fdout,0,0,count);
+  fs::fallocate(fdout,0,0,scount);
 
   rv = fs::sendfile(fdin,fdout,count);
   if((rv == -1) && ((errno == EINVAL) || (errno == ENOSYS)))
@@ -153,18 +154,18 @@ ignorable_error(const int err)
 
 namespace fs
 {
-  int
+  ssize_t
   clonefile(const int fdin,
             const int fdout)
   {
-    int rv;
+    ssize_t rv;
     struct stat stin;
 
     rv = fs::fstat(fdin,stin);
     if(rv == -1)
       return -1;
 
-    rv = ::copydata(fdin,fdout,stin.st_size,stin.st_blksize);
+    rv = ::copydata(fdin,fdout,(size_t)stin.st_size,(size_t)stin.st_blksize);
     if(rv == -1)
       return -1;
 
@@ -191,11 +192,11 @@ namespace fs
     return 0;
   }
 
-  int
+  ssize_t
   clonefile(const string &in,
             const string &out)
   {
-    int rv;
+    ssize_t rv;
     int fdin;
     int fdout;
     int error;
diff --git a/src/fs_inode.hpp b/src/fs_inode.hpp
index 7e07a7e0..683a83f0 100644
--- a/src/fs_inode.hpp
+++ b/src/fs_inode.hpp
@@ -34,7 +34,11 @@ namespace fs
     void
     recompute(struct stat &st)
     {
-      uint64_t st_dev = st.st_dev; /* Mac OS has a 32-bit device ID */
+      /*
+       Some OSes have 32-bit device IDs, so box this up first.
+       This does also presume a 64-bit inode value.
+       */
+      uint64_t st_dev = (uint64_t)st.st_dev;
       st.st_ino |= (st_dev << 32);
     }
   }
diff --git a/src/fs_movefile.cpp b/src/fs_movefile.cpp
index 1ca1fa54..b0271553 100644
--- a/src/fs_movefile.cpp
+++ b/src/fs_movefile.cpp
@@ -66,7 +66,7 @@ namespace fs
       return -1;
 
     fdin_st.st_size += additional_size;
-    rv = fs::mfs(basepaths,fdin_st.st_size,fdout_path);
+    rv = fs::mfs(basepaths,(uint64_t)fdin_st.st_size,fdout_path);
     if(rv == -1)
       return -1;
 
diff --git a/src/fs_xattr.cpp b/src/fs_xattr.cpp
index f468ac9e..94d9c764 100644
--- a/src/fs_xattr.cpp
+++ b/src/fs_xattr.cpp
@@ -63,19 +63,19 @@ using std::istringstream;
     return ::fgetxattr(fd, name, value, size, 0, 0);
   }
 
-  int
+  ssize_t
   _lgetxattr(const char* path, const char* name, char* value, size_t size)
   {
     return ::getxattr(path, name, value, size, 0, XATTR_NOFOLLOW);
   }
   
-  int
+  ssize_t
   _fsetxattr(int fd, const char* name, const char* value, size_t size, int flags)
   {
     return ::fsetxattr(fd, name, value, size, 0, flags);
   }
 
-  int
+  ssize_t
   _lsetxattr(const char* path, const char* name, const char* value, size_t size, int flags)
   {
     return ::setxattr(path, name, value, size, 0, flags && XATTR_NOFOLLOW);
@@ -94,7 +94,7 @@ namespace fs
 {
   namespace xattr
   {
-    int
+    ssize_t
     list(const int     fd,
          vector<char> &attrs)
     {
@@ -109,9 +109,9 @@ namespace fs
           if(rv <= 0)
             return rv;
 
-          attrs.resize(rv);
+          attrs.resize((size_t)rv);
 
-          rv = _flistxattr(fd,&attrs[0],rv);
+          rv = _flistxattr(fd,&attrs[0],(size_t)rv);
         }
 
       return rv;
@@ -120,7 +120,7 @@ namespace fs
 #endif
     }
 
-    int
+    ssize_t
     list(const string &path,
          vector<char> &attrs)
     {
@@ -135,9 +135,9 @@ namespace fs
           if(rv <= 0)
             return rv;
 
-          attrs.resize(rv);
+          attrs.resize((size_t)rv);
 
-          rv = _llistxattr(path.c_str(),&attrs[0],rv);
+          rv = _llistxattr(path.c_str(),&attrs[0],(size_t)rv);
         }
 
       return rv;
@@ -146,11 +146,11 @@ namespace fs
 #endif
     }
 
-    int
+    ssize_t
     list(const int        fd,
           vector<string> &attrvector)
     {
-      int rv;
+      ssize_t rv;
       vector<char> attrs;
 
       rv = list(fd,attrs);
@@ -163,11 +163,11 @@ namespace fs
       return rv;
     }
 
-    int
+    ssize_t
     list(const string   &path,
          vector<string> &attrvector)
     {
-      int rv;
+      ssize_t rv;
       vector<char> attrs;
 
       rv = list(path,attrs);
@@ -180,11 +180,11 @@ namespace fs
       return rv;
     }
 
-    int
+    ssize_t
     list(const int  fd,
          string    &attrstr)
     {
-      int rv;
+      ssize_t rv;
       vector<char> attrs;
 
       rv = list(fd,attrs);
@@ -194,11 +194,11 @@ namespace fs
       return rv;
     }
 
-    int
+    ssize_t
     list(const string &path,
          string       &attrstr)
     {
-      int rv;
+      ssize_t rv;
       vector<char> attrs;
 
       rv = list(path,attrs);
@@ -208,7 +208,7 @@ namespace fs
       return rv;
     }
 
-    int
+    ssize_t
     get(const int     fd,
         const string &attr,
         vector<char> &value)
@@ -224,9 +224,9 @@ namespace fs
           if(rv <= 0)
             return rv;
 
-          value.resize(rv);
+          value.resize((size_t)rv);
 
-          rv = _fgetxattr(fd,attr.c_str(),&value[0],rv);
+          rv = _fgetxattr(fd,attr.c_str(),&value[0],(size_t)rv);
         }
 
       return rv;
@@ -235,7 +235,7 @@ namespace fs
 #endif
     }
 
-    int
+    ssize_t
     get(const string &path,
         const string &attr,
         vector<char> &value)
@@ -251,9 +251,9 @@ namespace fs
           if(rv <= 0)
             return rv;
 
-          value.resize(rv);
+          value.resize((size_t)rv);
 
-          rv = _lgetxattr(path.c_str(),attr.c_str(),&value[0],rv);
+          rv = _lgetxattr(path.c_str(),attr.c_str(),&value[0],(size_t)rv);
         }
 
       return rv;
@@ -262,12 +262,12 @@ namespace fs
 #endif
     }
 
-    int
+    ssize_t
     get(const int     fd,
         const string &attr,
         string       &value)
     {
-      int          rv;
+      ssize_t          rv;
       vector<char> tmpvalue;
 
       rv = get(fd,attr,tmpvalue);
@@ -277,12 +277,12 @@ namespace fs
       return rv;
     }
 
-    int
+    ssize_t
     get(const string &path,
         const string &attr,
         string       &value)
     {
-      int          rv;
+      ssize_t          rv;
       vector<char> tmpvalue;
 
       rv = get(path,attr,tmpvalue);
@@ -292,11 +292,11 @@ namespace fs
       return rv;
     }
 
-    int
+    ssize_t
     get(const int           fd,
         map<string,string> &attrs)
     {
-      int rv;
+      ssize_t rv;
       string attrstr;
 
       rv = list(fd,attrstr);
@@ -320,11 +320,11 @@ namespace fs
       return 0;
     }
 
-    int
+    ssize_t
     get(const string       &path,
         map<string,string> &attrs)
     {
-      int rv;
+      ssize_t rv;
       string attrstr;
 
       rv = list(path,attrstr);
@@ -348,7 +348,7 @@ namespace fs
       return 0;
     }
 
-    int
+    ssize_t
     set(const int     fd,
         const string &key,
         const string &value,
@@ -365,7 +365,7 @@ namespace fs
 #endif
     }
 
-    int
+    ssize_t
     set(const string &path,
         const string &key,
         const string &value,
@@ -382,11 +382,11 @@ namespace fs
 #endif
     }
 
-    int
+    ssize_t
     set(const int                 fd,
         const map<string,string> &attrs)
     {
-      int rv;
+      ssize_t rv;
 
       for(map<string,string>::const_iterator
             i = attrs.begin(), ei = attrs.end(); i != ei; ++i)
@@ -414,11 +414,11 @@ namespace fs
       return fs::close(fd);
     }
 
-    int
+    ssize_t
     copy(const int fdin,
          const int fdout)
     {
-      int rv;
+      ssize_t rv;
       map<string,string> attrs;
 
       rv = get(fdin,attrs);
@@ -428,11 +428,11 @@ namespace fs
       return set(fdout,attrs);
     }
 
-    int
+    ssize_t
     copy(const string &from,
          const string &to)
     {
-      int rv;
+      ssize_t rv;
       map<string,string> attrs;
 
       rv = get(from,attrs);
diff --git a/src/getxattr.cpp b/src/getxattr.cpp
index 63536c4e..ce4b3c1c 100644
--- a/src/getxattr.cpp
+++ b/src/getxattr.cpp
@@ -39,13 +39,13 @@ using std::set;
 using namespace mergerfs;
 
 static
-int
+ssize_t
 _lgetxattr(const string &path,
            const char   *attrname,
            void         *value,
            const size_t  size)
 {
-  int rv;
+  ssize_t rv;
 
   rv = fs::lgetxattr(path,attrname,value,size);
 
@@ -153,7 +153,7 @@ _getxattr_pid(string &attrvalue)
 }
 
 static
-int
+ssize_t
 _getxattr_controlfile(const Config &config,
                       const char   *attrname,
                       char         *buf,
@@ -198,7 +198,7 @@ _getxattr_controlfile(const Config &config,
   len = attrvalue.size();
 
   if(count == 0)
-    return len;
+    return (ssize_t)len;
 
   if(count < len)
     return -ERANGE;
@@ -209,7 +209,7 @@ _getxattr_controlfile(const Config &config,
 }
 
 static
-int
+ssize_t
 _getxattr_from_string(char         *destbuf,
                       const size_t  destbufsize,
                       const string &src)
@@ -217,18 +217,18 @@ _getxattr_from_string(char         *destbuf,
   const size_t srcbufsize = src.size();
 
   if(destbufsize == 0)
-    return srcbufsize;
+    return (ssize_t)srcbufsize;
 
   if(srcbufsize > destbufsize)
     return -ERANGE;
 
   memcpy(destbuf,src.data(),srcbufsize);
 
-  return srcbufsize;
+  return (ssize_t)srcbufsize;
 }
 
 static
-int
+ssize_t
 _getxattr_user_mergerfs_allpaths(const vector<string> &srcmounts,
                                  const char           *fusepath,
                                  char                 *buf,
@@ -245,7 +245,7 @@ _getxattr_user_mergerfs_allpaths(const vector<string> &srcmounts,
 }
 
 static
-int
+ssize_t
 _getxattr_user_mergerfs(const string         &basepath,
                         const char           *fusepath,
                         const string         &fullpath,
@@ -271,7 +271,7 @@ _getxattr_user_mergerfs(const string         &basepath,
 }
 
 static
-int
+ssize_t
 _getxattr(Policy::Func::Search  searchFunc,
           const vector<string> &srcmounts,
           const size_t          minfreespace,
@@ -280,7 +280,7 @@ _getxattr(Policy::Func::Search  searchFunc,
           char                 *buf,
           const size_t          count)
 {
-  int rv;
+  ssize_t rv;
   string fullpath;
   vector<const string*> basepaths;
 
@@ -303,14 +303,14 @@ namespace mergerfs
   namespace fuse
   {
 #if __APPLE__
-    int
+    ssize_t
     getxattr(const char *fusepath,
              const char *attrname,
              char       *buf,
              size_t      count,
              uint32_t    position)
 #else
-    int
+    ssize_t
     getxattr(const char *fusepath,
              const char *attrname,
              char       *buf,
@@ -331,7 +331,7 @@ namespace mergerfs
 
       return _getxattr(config.getxattr,
                        config.srcmounts,
-                       config.minfreespace,
+               (size_t)config.minfreespace,
                        fusepath,
                        attrname,
                        buf,
diff --git a/src/gidcache.cpp b/src/gidcache.cpp
index 0d5afbfb..995e0d6e 100644
--- a/src/gidcache.cpp
+++ b/src/gidcache.cpp
@@ -66,8 +66,8 @@ gid_t_cache::lower_bound(gid_t_rec   *begin,
                          gid_t_rec   *end,
                          const uid_t  uid)
 {
-  int step;
-  int count;
+  long step;
+  long count;
   gid_t_rec *iter;
 
   count = std::distance(begin,end);
@@ -106,15 +106,19 @@ gid_t_cache::cache(const uid_t uid,
   rv = ::getpwuid_r(uid,&pwd,buf,sizeof(buf),&pwdrv);
   if(pwdrv != NULL && rv == 0)
     {
+ #if __APPLE__
+      // OSX:   getgrouplist(const char *name, int basegid, int *groups, int *ngroups)
       rec->size = 0;
-      ::getgrouplist(pwd.pw_name,gid,NULL,&rec->size);
+      ::getgrouplist(pwd.pw_name,(int)gid,NULL,&rec->size);
       rec->size = std::min(MAXGIDS,rec->size);
       
- #if __APPLE__ 
-      // OSX:   getgrouplist(const char *name, int basegid, int *groups, int *ngroups)
-      rv = ::getgrouplist(pwd.pw_name,gid,(int*)rec->gids,&rec->size);
+      rv = ::getgrouplist(pwd.pw_name,(int)gid,(int*)rec->gids,&rec->size);
 #else
       // Linux: getgrouplist(const char *name, gid_t group, gid_t *groups int *ngroups)
+      rec->size = 0;
+      ::getgrouplist(pwd.pw_name,gid,NULL,&rec->size);
+      rec->size = std::min(MAXGIDS,rec->size);
+      
       rv = ::getgrouplist(pwd.pw_name,gid,rec->gids,&rec->size);
 #endif
       
diff --git a/src/ioctl.cpp b/src/ioctl.cpp
index c081bfc9..c3aa89f1 100644
--- a/src/ioctl.cpp
+++ b/src/ioctl.cpp
@@ -37,9 +37,9 @@ using namespace mergerfs;
 
 static
 int
-_ioctl(const int  fd,
-       const int  cmd,
-       void      *data)
+_ioctl(const int            fd,
+       const unsigned long  cmd,
+       void                *data)
 {
   int rv;
 
@@ -60,7 +60,7 @@ _ioctl_dir_base(Policy::Func::Search  searchFunc,
                 const vector<string> &srcmounts,
                 const uint64_t        minfreespace,
                 const char           *fusepath,
-                const int             cmd,
+                const unsigned long   cmd,
                 void                 *data)
 {
   int fd;
@@ -88,9 +88,9 @@ _ioctl_dir_base(Policy::Func::Search  searchFunc,
 
 static
 int
-_ioctl_dir(const char *fusepath,
-           const int   cmd,
-           void       *data)
+_ioctl_dir(const char         *fusepath,
+           const unsigned long cmd,
+           void               *data)
 {
   const fuse_context      *fc     = fuse_get_context();
   const Config            &config = Config::get(fc);
@@ -121,13 +121,13 @@ namespace mergerfs
 #ifdef FUSE_IOCTL_DIR
       if(flags & FUSE_IOCTL_DIR)
         return _ioctl_dir(fusepath,
-                          cmd,
+           (unsigned long)cmd,
                           data);
 #endif
       FileInfo *fi = reinterpret_cast<FileInfo*>(ffi->fh);
 
       return _ioctl(fi->fd,
-                    cmd,
+     (unsigned long)cmd,
                     data);
     }
   }
diff --git a/src/listxattr.cpp b/src/listxattr.cpp
index b84be9ef..1c723f29 100644
--- a/src/listxattr.cpp
+++ b/src/listxattr.cpp
@@ -36,7 +36,7 @@ using std::vector;
 using namespace mergerfs;
 
 static
-int
+ssize_t
 _listxattr_controlfile(char         *list,
                        const size_t  size)
 {
@@ -59,18 +59,18 @@ _listxattr_controlfile(char         *list,
     xattrs += ("user.mergerfs.func." + (std::string)*FuseFunc::fusefuncs[i] + '\0');
 
   if(size == 0)
-    return xattrs.size();
+    return (ssize_t)xattrs.size();
 
   if(size < xattrs.size())
     return -ERANGE;
 
   memcpy(list,xattrs.c_str(),xattrs.size());
 
-  return xattrs.size();
+  return (ssize_t)xattrs.size();
 }
 
 static
-int
+ssize_t
 _listxattr(Policy::Func::Search  searchFunc,
            const vector<string> &srcmounts,
            const uint64_t        minfreespace,
@@ -78,7 +78,7 @@ _listxattr(Policy::Func::Search  searchFunc,
            char                 *list,
            const size_t          size)
 {
-  int rv;
+  ssize_t rv;
   string fullpath;
   vector<const string*> basepaths;
 
@@ -97,7 +97,7 @@ namespace mergerfs
 {
   namespace fuse
   {
-    int
+    ssize_t
     listxattr(const char *fusepath,
               char       *list,
               size_t      size)
diff --git a/src/mergerfs.cpp b/src/mergerfs.cpp
index 5b65b732..43aa2e62 100644
--- a/src/mergerfs.cpp
+++ b/src/mergerfs.cpp
@@ -142,7 +142,7 @@ namespace local
   {
     const int prio = -10;
 
-    std::srand(time(NULL));
+    std::srand((unsigned int)time(NULL));
     mergerfs::resources::reset_umask();
     mergerfs::resources::maxout_rlimit_nofile();
     mergerfs::resources::maxout_rlimit_fsize();
diff --git a/src/num.cpp b/src/num.cpp
index 7f6a0ec4..3e1894ca 100644
--- a/src/num.cpp
+++ b/src/num.cpp
@@ -28,7 +28,7 @@ namespace num
     char *endptr;
     uint64_t tmp;
 
-    tmp = strtoll(str.c_str(),&endptr,10);
+    tmp = strtoul(str.c_str(),&endptr,10);
     switch(*endptr)
       {
       case 'k':
diff --git a/src/read.cpp b/src/read.cpp
index 80d08c09..e3b8ea71 100644
--- a/src/read.cpp
+++ b/src/read.cpp
@@ -26,32 +26,30 @@
 
 static
 inline
-int
+ssize_t
 _read(const int     fd,
       void         *buf,
       const size_t  count,
       const off_t   offset)
 {
-  int rv;
+  ssize_t rv;
 
   rv = fs::pread(fd,buf,count,offset);
   if(rv == -1)
     return -errno;
-  if(rv == 0)
-    return 0;
 
-  return count;
+  return rv;
 }
 
 static
 inline
-int
+ssize_t
 _read_direct_io(const int     fd,
                 void         *buf,
                 const size_t  count,
                 const off_t   offset)
 {
-  int rv;
+  ssize_t rv;
 
   rv = fs::pread(fd,buf,count,offset);
   if(rv == -1)
@@ -64,7 +62,7 @@ namespace mergerfs
 {
   namespace fuse
   {
-    int
+    ssize_t
     read(const char     *fusepath,
          char           *buf,
          size_t          count,
@@ -76,7 +74,7 @@ namespace mergerfs
       return _read(fi->fd,buf,count,offset);
     }
 
-    int
+    ssize_t
     read_direct_io(const char     *fusepath,
                    char           *buf,
                    size_t          count,
diff --git a/src/readdir.cpp b/src/readdir.cpp
index 56d8e054..c8d5d775 100644
--- a/src/readdir.cpp
+++ b/src/readdir.cpp
@@ -50,7 +50,7 @@ _readdir(const vector<string>  &srcmounts,
          void                  *buf,
          const fuse_fill_dir_t  filler)
 {
-  StrSet names;
+  StrSet names = StrSet();
   string basepath;
   struct stat st = {0};
 
@@ -69,7 +69,7 @@ _readdir(const vector<string>  &srcmounts,
       dirfd     = fs::dirfd(dh);
       st.st_dev = fs::devid(dirfd);
       if(st.st_dev == (dev_t)-1)
-        st.st_dev = i;
+        st.st_dev = (dev_t)i;
 
       rv = 0;
       for(struct dirent *de = fs::readdir(dh); de && !rv; de = fs::readdir(dh))
@@ -79,7 +79,7 @@ _readdir(const vector<string>  &srcmounts,
             continue;
 
           st.st_ino  = de->d_ino;
-          st.st_mode = DTTOIF(de->d_type);
+          st.st_mode = (mode_t)DTTOIF(de->d_type);
 
           fs::inode::recompute(st);
 
diff --git a/src/readlink.cpp b/src/readlink.cpp
index b484b052..e5b4f486 100644
--- a/src/readlink.cpp
+++ b/src/readlink.cpp
@@ -28,13 +28,13 @@ using std::vector;
 using mergerfs::Policy;
 
 static
-int
+ssize_t
 _readlink_core(const string *basepath,
                const char   *fusepath,
                char         *buf,
                const size_t  size)
 {
-  int rv;
+  ssize_t rv;
   string fullpath;
 
   fs::path::make(basepath,fusepath,fullpath);
@@ -49,7 +49,7 @@ _readlink_core(const string *basepath,
 }
 
 static
-int
+ssize_t
 _readlink(Policy::Func::Search  searchFunc,
           const vector<string> &srcmounts,
           const uint64_t        minfreespace,
@@ -57,7 +57,7 @@ _readlink(Policy::Func::Search  searchFunc,
           char                 *buf,
           const size_t          size)
 {
-  int rv;
+  ssize_t rv;
   vector<const string*> basepaths;
 
   rv = searchFunc(srcmounts,fusepath,minfreespace,basepaths);
@@ -71,7 +71,7 @@ namespace mergerfs
 {
   namespace fuse
   {
-    int
+    ssize_t
     readlink(const char *fusepath,
              char       *buf,
              size_t      size)
diff --git a/src/ugid_rwlock.hpp b/src/ugid_rwlock.hpp
index 0c4dfd23..580a2ec8 100644
--- a/src/ugid_rwlock.hpp
+++ b/src/ugid_rwlock.hpp
@@ -48,13 +48,13 @@ namespace mergerfs
 
       if(currentuid != 0)
         {
-          ::seteuid(0);
-          ::setegid(0);
+          (void)::seteuid(0);
+          (void)::setegid(0);
         }
 
       if(newgid)
         {
-          ::setegid(newgid);
+          (void)::setegid(newgid);
           initgroups(newuid,newgid);
         }
 
diff --git a/src/write.cpp b/src/write.cpp
index 6d722b06..be1f5deb 100644
--- a/src/write.cpp
+++ b/src/write.cpp
@@ -26,7 +26,7 @@
 
 using namespace mergerfs;
 
-typedef int (*WriteFunc)(const int,const void*,const size_t,const off_t);
+typedef ssize_t (*WriteFunc)(const int,const void*,const size_t,const off_t);
 
 static
 bool
@@ -38,32 +38,30 @@ _out_of_space(const int error)
 
 static
 inline
-int
+ssize_t
 _write(const int     fd,
        const void   *buf,
        const size_t  count,
        const off_t   offset)
 {
-  int rv;
+  ssize_t rv;
 
   rv = fs::pwrite(fd,buf,count,offset);
   if(rv == -1)
     return -errno;
-  if(rv == 0)
-    return 0;
 
-  return count;
+  return rv;
 }
 
 static
 inline
-int
+ssize_t
 _write_direct_io(const int     fd,
                  const void   *buf,
                  const size_t  count,
                  const off_t   offset)
 {
-  int rv;
+  ssize_t rv;
 
   rv = fs::pwrite(fd,buf,count,offset);
   if(rv == -1)
@@ -81,7 +79,7 @@ namespace mergerfs
   {
     static
     inline
-    int
+    ssize_t
     write(WriteFunc       func,
           const char     *fusepath,
           const char     *buf,
@@ -89,11 +87,11 @@ namespace mergerfs
           const off_t     offset,
           fuse_file_info *ffi)
     {
-      int rv;
+      ssize_t rv;
       FileInfo* fi = reinterpret_cast<FileInfo*>(ffi->fh);
 
       rv = func(fi->fd,buf,count,offset);
-      if(_out_of_space(-rv))
+      if(_out_of_space((int)-rv))
         {
           const fuse_context *fc     = fuse_get_context();
           const Config       &config = Config::get(fc);
@@ -114,7 +112,7 @@ namespace mergerfs
       return rv;
     }
 
-    int
+    ssize_t
     write(const char     *fusepath,
           const char     *buf,
           size_t          count,
@@ -124,7 +122,7 @@ namespace mergerfs
       return write(_write,fusepath,buf,count,offset,ffi);
     }
 
-    int
+    ssize_t
     write_direct_io(const char     *fusepath,
                     const char     *buf,
                     size_t          count,
diff --git a/src/write_buf.cpp b/src/write_buf.cpp
index db262436..44f08dff 100644
--- a/src/write_buf.cpp
+++ b/src/write_buf.cpp
@@ -46,7 +46,7 @@ _out_of_space(const int error)
 }
 
 static
-int
+ssize_t
 _write_buf(const int    fd,
            fuse_bufvec &src,
            const off_t  offset)
@@ -67,17 +67,17 @@ namespace mergerfs
 {
   namespace fuse
   {
-    int
+    ssize_t
     write_buf(const char     *fusepath,
               fuse_bufvec    *src,
               off_t           offset,
               fuse_file_info *ffi)
     {
-      int rv;
+      ssize_t rv;
       FileInfo *fi = reinterpret_cast<FileInfo*>(ffi->fh);
 
       rv = _write_buf(fi->fd,*src,offset);
-      if(_out_of_space(-rv))
+      if(_out_of_space((int)-rv))
         {
           const fuse_context *fc     = fuse_get_context();
           const Config       &config = Config::get(fc);