diff --git a/src/base/config.c b/src/base/config.c
index 568a64f9751472b50160b400f93d955d5dc6165f..6e4a44b625d4a2a2c1b30971053a2fc537016cef 100644
--- a/src/base/config.c
+++ b/src/base/config.c
@@ -211,7 +211,7 @@ config_default_file(char *dest, size_t len)
     } else {
         LOG_DEBUG("CONFIG", "Using XDG_CONFIG_HOME: %s", home);
         safe_strncpy(dest, home, len - 1);
-        strncat(dest, "/lektor/lektor.ini", len - 1);
+        strncat(dest, "/lektor/lektor.ini", len - 1 - strlen(home));
     }
 }