diff --git a/server/tests/test-glib-compat.h b/server/tests/test-glib-compat.h
index eef07494..17ebcf48 100644
--- a/server/tests/test-glib-compat.h
+++ b/server/tests/test-glib-compat.h
@@ -70,7 +70,7 @@ g_test_assert_expected_messages_internal_no_warnings(const char *domain,
 
 /* Added in glib 2.50 */
 #ifndef G_PID_FORMAT
-#ifdef G_OS_WIN32
+#ifndef G_OS_WIN32
 #define G_PID_FORMAT "i"
 #else
 #define G_PID_FORMAT "p"