diff --git a/libfuse/lib/debug.cpp b/libfuse/lib/debug.cpp
index 8f8de0f5..57ddf208 100644
--- a/libfuse/lib/debug.cpp
+++ b/libfuse/lib/debug.cpp
@@ -1279,7 +1279,7 @@ debug_fuse_out_header(const struct fuse_out_header *hdr_)
   fmt::print(g_OUTPUT,
              "unique=0x{:016x};"
              " opcode=RESPONSE;"
-             " error=%d (%s);"
+             " error={} ({});"
              " len={};"
              ,
              hdr_->unique,