o_str.h isn't a public header file.
diff --git a/e_os.h b/e_os.h
index aae3c79..0977416 100644
--- a/e_os.h
+++ b/e_os.h
@@ -548,7 +548,7 @@
 #  define strncasecmp _strnicmp
 #elif defined(OPENSSL_SYS_VMS)
 /* VMS below version 7.0 doesn't have strcasecmp() */
-#  include <openssl/o_str.h>
+#  include "o_str.h"
 #  define strcasecmp OPENSSL_strcasecmp
 #  define strncasecmp OPENSSL_strncasecmp
 #elif defined(OPENSSL_SYS_OS2) && defined(__EMX__)