diff --git a/lib/base/common_plugin.h b/lib/base/common_plugin.h
index 27dace944..82c589563 100644
--- a/lib/base/common_plugin.h
+++ b/lib/base/common_plugin.h
@@ -37,19 +37,25 @@
 #define HEIMDAL_BASE_COMMON_PLUGIN_H
 
 #ifdef _WIN32
-#ifndef HEIM_CALLCONV
-#define HEIM_CALLCONV __stdcall
-#endif
-#ifndef HEIM_LIB_CALL
-#define HEIM_LIB_CALL __stdcall
-#endif
+# ifndef HEIM_CALLCONV
+#  define HEIM_CALLCONV __stdcall
+# endif
+# ifndef HEIM_LIB_CALL
+#  define HEIM_LIB_CALL __stdcall
+# endif
 #else
-#ifndef HEIM_CALLCONV
-#define HEIM_CALLCONV
+# ifndef HEIM_CALLCONV
+#  define HEIM_CALLCONV
+# endif
+# ifndef HEIM_LIB_CALL
+#  define HEIM_LIB_CALL
+# endif
 #endif
-#ifndef HEIM_LIB_CALL
-#define HEIM_LIB_CALL
+#ifndef KRB5_CALLCONV
+# define KRB5_CALLCONV HEIM_CALLCONV
 #endif
+#ifndef KRB5_LIB_CALL
+# define KRB5_LIB_CALL HEIM_LIB_CALL
 #endif
 
 /* For krb5 plugins, this is a krb5_context */