diff --git a/libc/hdr/types/mbstate_t.h b/libc/hdr/types/mbstate_t.h
index 367c6af7a3ffb..d8fadceaaac8d 100644
--- a/libc/hdr/types/mbstate_t.h
+++ b/libc/hdr/types/mbstate_t.h
@@ -15,7 +15,7 @@
 
 #else // Overlay mode
 
-#error "Cannot overlay mbstate_t
+#error "Cannot overlay mbstate_t"
 
 #endif // LLVM_LIBC_FULL_BUILD