diff --git a/src/strnlen.h b/src/strnlen.h
index 007da2e55..fdd7fe39c 100644
--- a/src/strnlen.h
+++ b/src/strnlen.h
@@ -7,7 +7,7 @@
 #ifndef INCLUDE_strlen_h__
 #define INCLUDE_strlen_h__
 
-#if defined(__MINGW32__) || defined(__sun) || defined(__APPLE__)
+#if defined(__MINGW32__) || defined(__sun) || defined(__APPLE__) || defined(__MidnightBSD__)
 #   define NO_STRNLEN
 #endif