diff --git a/src/_cocoalayer.h b/src/_cocoalayer.h
index a1990b39a..f7afe6560 100644
--- a/src/_cocoalayer.h
+++ b/src/_cocoalayer.h
@@ -1,3 +1,13 @@
 #ifdef __APPLE__
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+void CocoaSetDockIcon(unsigned char* data, int width, int height);
+
+#ifdef __cplusplus
+}
+#endif
+
 #endif