diff --git a/src/services/findAllReferences.ts b/src/services/findAllReferences.ts
index 92ca47cbed6..5687bbfc02b 100644
--- a/src/services/findAllReferences.ts
+++ b/src/services/findAllReferences.ts
@@ -334,7 +334,7 @@ namespace ts.FindAllReferences.Core {
                     references.push({ type: "node", node: (decl as ts.ModuleDeclaration).name });
                     break;
                 default:
-                    Debug.assert(false);
+                    Debug.fail("Expected a module symbol to be declared by a SourceFile or ModuleDeclaration.");
             }
         }
 
diff --git a/src/services/importTracker.ts b/src/services/importTracker.ts
index e8528b366b9..2866ade873b 100644
--- a/src/services/importTracker.ts
+++ b/src/services/importTracker.ts
@@ -405,7 +405,7 @@ namespace ts.FindAllReferences {
             case SyntaxKind.ExternalModuleReference:
                 return (decl as ExternalModuleReference).parent;
             default:
-                Debug.assert(false);
+                Debug.fail(`Unexpected module specifier parent: ${decl.kind}`);
         }
     }