stdio_ext.h needs to include stdio.h, at least to get FILE...
diff --git a/include/stdio_ext.h b/include/stdio_ext.h
index d979bdc..e3ab7fd 100644
--- a/include/stdio_ext.h
+++ b/include/stdio_ext.h
@@ -5,6 +5,8 @@
 extern "C" {
 #endif
 
+#include <stdio.h>
+
 #define FSETLOCKING_QUERY 0
 #define FSETLOCKING_INTERNAL 1
 #define FSETLOCKING_BYCALLER 2