--- src/gpg-error.h.in
+++ src/gpg-error.h.in
@@ -152,7 +152,7 @@
 /*
  * GCC feature test.
  */
-#if __GNUC__
+#ifdef __GNUC__
 # define _GPG_ERR_GCC_VERSION (__GNUC__ * 10000 \
                                + __GNUC_MINOR__ * 100 \
                                + __GNUC_PATCHLEVEL__)