--- a/src/main.c
+++ b/src/main.c
@@ -39,7 +39,7 @@
 #include <sys/types.h>
 #include <sys/stat.h>
 
-GdkPixbuf* gdkTreeSize;
+extern GdkPixbuf* gdkTreeSize;
 GtkMenu *TreeSizeMenuGlobal;
 GtkWidget *mainWindow;