diff --git a/magick/exception-private.h b/magick/exception-private.h
index f49ad97..558c60b 100644
--- a/magick/exception-private.h
+++ b/magick/exception-private.h
@@ -23,6 +23,7 @@
 #endif
 
 #include "magick/log.h"
+#include "magick/string_.h"
 
 #define ThrowBinaryException(severity,tag,context) \
 { \