diff --git a/src/bindings/csharp/openalpr-net/openalpr-net.h b/src/bindings/csharp/openalpr-net/openalpr-net.h
index 52ec33e..ca26c5e 100644
--- a/src/bindings/csharp/openalpr-net/openalpr-net.h
+++ b/src/bindings/csharp/openalpr-net/openalpr-net.h
@@ -1,6 +1,7 @@
 #pragma once
 
 #include "alpr.h"
+#include "prewarp.h"
 
 #include <stdlib.h>
 #include <string.h>