diff --git a/package.json b/package.json
index 43421a17c..55c41f56d 100644
--- a/package.json
+++ b/package.json
@@ -1,7 +1,7 @@
 {
   "name": "vscode-chrome-debug-core",
   "displayName": "vscode-chrome-debug-core",
-  "version": "3.12.2",
+  "version": "3.12.3",
   "description": "A library for building VS Code debug adapters for targets that support the Chrome Remote Debug Protocol",
   "repository": {
     "type": "git",
diff --git a/src/chrome/chromeDebugAdapter.ts b/src/chrome/chromeDebugAdapter.ts
index 1ef8af3c6..e532b7fd9 100644
--- a/src/chrome/chromeDebugAdapter.ts
+++ b/src/chrome/chromeDebugAdapter.ts
@@ -1760,7 +1760,7 @@ export abstract class ChromeDebugAdapter implements IDebugAdapter {
 
     private displayNameForSourceReference(sourceReference: number): string {
         const handle = this._sourceHandles.get(sourceReference);
-        return this.displayNameForScriptId(handle.scriptId);
+        return (handle && this.displayNameForScriptId(handle.scriptId)) || sourceReference + '';
     }
 
     private displayNameForScriptId(scriptId: number|string): string {