diff --git a/BUILD.gn b/BUILD.gn
index 96e24183..357e358 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -5,10 +5,12 @@
 config("wuffs_public") {
   include_dirs = [ "release/c" ]
 
-  cflags = [
-    "-Wno-unused-function",
-    "-Wno-c++11-narrowing",
-  ]
+  if (is_clang) {
+    cflags += [
+      "-Wno-unused-function",
+      "-Wno-c++11-narrowing",
+    ]
+  }
 }
 
 source_set("wuffs") {