diff --git a/libc/stdio/local.h b/libc/stdio/local.h
index 46b11f1..7033eda 100644
--- a/libc/stdio/local.h
+++ b/libc/stdio/local.h
@@ -111,8 +111,8 @@
 	(fp)->_lb._base = NULL; \
 }
 
-#define FLOCKFILE(fp)   flockfile(fp)
-#define FUNLOCKFILE(fp) funlockfile(fp)
+#define FLOCKFILE(fp)   if (_EXT(fp)->_stdio_handles_locking) flockfile(fp)
+#define FUNLOCKFILE(fp) if (_EXT(fp)->_stdio_handles_locking) funlockfile(fp)
 
 #define FLOATING_POINT
 #define PRINTF_WIDE_CHAR