diff --git a/src/base/config.c b/src/base/config.c
index 0d77197a2bd26160a0db45f4258b20dee0490d02..73399960e0e1efe0387e2648015b1d667f7ee7b1 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));
     }
 }