diff --git a/src/config.cpp b/src/config.cpp
index 8ac7638b..2304ae3f 100644
--- a/src/config.cpp
+++ b/src/config.cpp
@@ -325,7 +325,8 @@ Config::keys(std::string &s_) const
       s_ += '\0';
     }
 
-  s_.resize(s_.size() - 1);
+  if(!s_.empty())
+    s_.resize(s_.size() - 1);
 }