diff --git a/libc/bionic/locale.cpp b/libc/bionic/locale.cpp
index 681e038..90aa7b8 100644
--- a/libc/bionic/locale.cpp
+++ b/libc/bionic/locale.cpp
@@ -26,6 +26,7 @@
  * SUCH DAMAGE.
  */
 
+#include <errno.h>
 #include <locale.h>
 #include <pthread.h>
 #include <stdlib.h>