diff --git a/build/lib/tsb/builder.js b/build/lib/tsb/builder.js
index 84308191361..0da1f5c09e6 100644
--- a/build/lib/tsb/builder.js
+++ b/build/lib/tsb/builder.js
@@ -558,10 +558,11 @@ class LanguageServiceHost {
         return old;
     }
     removeScriptSnapshot(filename) {
+        filename = normalize(filename);
+        this._log('removeScriptSnapshot', filename);
         this._filesInProject.delete(filename);
         this._filesAdded.delete(filename);
         this._projectVersion++;
-        filename = normalize(filename);
         delete this._fileNameToDeclaredModule[filename];
         return delete this._snapshots[filename];
     }
@@ -622,6 +623,9 @@ 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 7a1b0e0cbb4..1a68131f86d 100644
--- a/build/lib/tsb/builder.ts
+++ b/build/lib/tsb/builder.ts
@@ -630,10 +630,11 @@ class LanguageServiceHost implements ts.LanguageServiceHost {
 	}
 
 	removeScriptSnapshot(filename: string): boolean {
+		filename = normalize(filename);
+		this._log('removeScriptSnapshot', filename);
 		this._filesInProject.delete(filename);
 		this._filesAdded.delete(filename);
 		this._projectVersion++;
-		filename = normalize(filename);
 		delete this._fileNameToDeclaredModule[filename];
 		return delete this._snapshots[filename];
 	}
@@ -706,7 +707,9 @@ class LanguageServiceHost implements ts.LanguageServiceHost {
 				// node module?
 				return;
 			}
-
+			if (ref.fileName.endsWith('.css')) {
+				return;
+			}
 
 			const stopDirname = normalize(this.getCurrentDirectory());
 			let dirname = filename;