diff --git a/src/services/inlayHints.ts b/src/services/inlayHints.ts
index ef4abe8dce6a4..11ba48dbd5670 100644
--- a/src/services/inlayHints.ts
+++ b/src/services/inlayHints.ts
@@ -753,9 +753,8 @@ export function provideInlayHints(context: InlayHintsContext): InlayHint[] {
                     break;
                 case SyntaxKind.IndexSignature:
                     Debug.assertNode(node, isIndexSignatureDeclaration);
-                    Debug.assertEqual(node.parameters.length, 1);
                     parts.push({ text: "[" });
-                    visitForDisplayParts(node.parameters[0]);
+                    visitDisplayPartList(node.parameters, ", ");
                     parts.push({ text: "]" });
                     if (node.type) {
                         parts.push({ text: ": " });