diff --git a/version.h b/version.h
index 3f6d8215bc..f9ac368e3b 100644
--- a/version.h
+++ b/version.h
@@ -52,9 +52,6 @@
 #   define RUBY_BRANCH_NAME "trunk"
 #  endif
 #  define RUBY_REVISION_STR " "RUBY_BRANCH_NAME" "RUBY_REVISION
-#  ifndef RUBY_RELEASE_DATETIME
-#   define RUBY_RELEASE_DATETIME RUBY_RELEASE_DATE
-#  endif
 # else
 #  define RUBY_REVISION_STR " revision "RUBY_REVISION
 # endif
@@ -62,6 +59,10 @@
 # define RUBY_REVISION "HEAD"
 # define RUBY_REVISION_STR ""
 #endif
+#if !defined RUBY_RELEASE_DATETIME || RUBY_PATCHLEVEL != -1
+# undef RUBY_RELEASE_DATETIME
+# define RUBY_RELEASE_DATETIME RUBY_RELEASE_DATE
+#endif
 
 # define RUBY_DESCRIPTION_WITH(opt) \
     "ruby "RUBY_VERSION		    \