diff --git a/uwac/libuwac/uwac-os.c b/uwac/libuwac/uwac-os.c
index 799cdce9a..4f8c8f516 100644
--- a/uwac/libuwac/uwac-os.c
+++ b/uwac/libuwac/uwac-os.c
@@ -33,6 +33,11 @@
 #define USE_SHM
 #endif
 
+/* uClibc and uClibc-ng don't provide O_TMPFILE */
+#ifndef O_TMPFILE
+#define O_TMPFILE (020000000 | O_DIRECTORY)
+#endif
+
 #include <sys/types.h>
 #include <sys/socket.h>
 #ifdef USE_SHM