diff --git a/crypto/o_str.c b/crypto/o_str.c
index 7189d1335..5a78f3250 100644
--- a/crypto/o_str.c
+++ b/crypto/o_str.c
@@ -57,12 +57,7 @@
  */
 
 #include <ctype.h>
-#include <openssl/e_os2.h>
-#ifdef OPENSSL_SYS_WINDOWS
-# include <string.h>
-#else
-# include <strings.h>
-#endif
+#include <e_os.h>
 #include "o_str.h"
 
 #undef strncasecmp