diff --git a/winsup/cygwin/ChangeLog b/winsup/cygwin/ChangeLog
index 550490a62..cd2dbb92f 100644
--- a/winsup/cygwin/ChangeLog
+++ b/winsup/cygwin/ChangeLog
@@ -1,3 +1,7 @@
+2015-03-10  Yaakov Selkowitz  <yselkowitz@cygwin.com>
+
+	* include/stdint.h: Fix __x86_64__ conditional.
+
 2015-03-05  Corinna Vinschen  <corinna@vinschen.de>
 
 	* tty.h (tty::set_master_ctl_closed): Rename from set_master_closed.
diff --git a/winsup/cygwin/include/stdint.h b/winsup/cygwin/include/stdint.h
index b670884a7..94b6b7673 100644
--- a/winsup/cygwin/include/stdint.h
+++ b/winsup/cygwin/include/stdint.h
@@ -114,7 +114,7 @@ typedef unsigned long long uintmax_t;
 #if !defined (__cplusplus) || defined (__STDC_LIMIT_MACROS) \
     || defined (__INSIDE_CYGWIN__)
 
-#if __x86_64__
+#ifdef __x86_64__
 # define __I64(n) n ## L
 # define __U64(n) n ## UL
 #else