diff --git a/src/google/protobuf/stubs/port.h b/src/google/protobuf/stubs/port.h
index 376be5f7ab..d5ef166e44 100644
--- a/src/google/protobuf/stubs/port.h
+++ b/src/google/protobuf/stubs/port.h
@@ -60,8 +60,12 @@
   #endif
 #else
   #include <sys/param.h>   // __BYTE_ORDER
+  #if defined(__OpenBSD__)
+    #include <endian.h>
+  #endif
   #if ((defined(__LITTLE_ENDIAN__) && !defined(__BIG_ENDIAN__)) || \
-         (defined(__BYTE_ORDER) && __BYTE_ORDER == __LITTLE_ENDIAN)) && \
+         (defined(__BYTE_ORDER) && __BYTE_ORDER == __LITTLE_ENDIAN) || \
+         (defined(BYTE_ORDER) && BYTE_ORDER == LITTLE_ENDIAN)) && \
       !defined(PROTOBUF_DISABLE_LITTLE_ENDIAN_OPT_FOR_TEST)
     #define PROTOBUF_LITTLE_ENDIAN 1
   #endif