diff --git a/build/lib/tsb/builder.js b/build/lib/tsb/builder.js
index c039131a57d..9ecd9bdea5b 100644
--- a/build/lib/tsb/builder.js
+++ b/build/lib/tsb/builder.js
@@ -586,6 +586,9 @@ class LanguageServiceHost {
                 // node module?
                 return;
             }
+            if (ref.fileName.endsWith('.css')) {
+                return;
+            }
             const stopDirname = normalize(this.getCurrentDirectory());
             let dirname = filename;
             let found = false;
diff --git a/build/lib/tsb/builder.ts b/build/lib/tsb/builder.ts
index 53e9f597e51..e60a2ecfad8 100644
--- a/build/lib/tsb/builder.ts
+++ b/build/lib/tsb/builder.ts
@@ -706,7 +706,9 @@ class LanguageServiceHost implements ts.LanguageServiceHost {
 				// node module?
 				return;
 			}
-
+			if (ref.fileName.endsWith('.css')) {
+				return;
+			}
 
 			const stopDirname = normalize(this.getCurrentDirectory());
 			let dirname = filename;