diff --git a/crypto/o_str.c b/crypto/o_str.c
index 0bdfb40076..42b25d078f 100644
--- a/crypto/o_str.c
+++ b/crypto/o_str.c
@@ -61,6 +61,9 @@
 #include "o_str.h"
 #include <openssl/e_os2.h>
 
+#undef strncasecmp
+#undef strcasecmp
+
 int OPENSSL_strncasecmp(const char *str1, const char *str2, size_t n)
 	{
 #if defined(OPENSSL_SYS_VMS)