diff --git a/lib/includes/nghttp2/nghttp2.h b/lib/includes/nghttp2/nghttp2.h
index 8c54b9c8..deaba757 100644
--- a/lib/includes/nghttp2/nghttp2.h
+++ b/lib/includes/nghttp2/nghttp2.h
@@ -31,6 +31,11 @@
 #  define WIN32
 #endif
 
+/* Compatibility for non-Clang compilers */
+#ifndef __has_declspec_attribute
+#  define __has_declspec_attribute(x) 0
+#endif
+
 #ifdef __cplusplus
 extern "C" {
 #endif
@@ -51,7 +56,7 @@ extern "C" {
 
 #ifdef NGHTTP2_STATICLIB
 #  define NGHTTP2_EXTERN
-#elif defined(WIN32)
+#elif defined(WIN32) || (__has_declspec_attribute(dllexport) && __has_declspec_attribute(dllimport))
 #  ifdef BUILDING_NGHTTP2
 #    define NGHTTP2_EXTERN __declspec(dllexport)
 #  else /* !BUILDING_NGHTTP2 */