diff --git a/packages/ai/src/providers/openai-completions.ts b/packages/ai/src/providers/openai-completions.ts
index 7150af2b..f724401b 100644
--- a/packages/ai/src/providers/openai-completions.ts
+++ b/packages/ai/src/providers/openai-completions.ts
@@ -129,7 +129,7 @@ export const streamOpenAICompletions: StreamFunction<"openai-completions", OpenA
 							partial: output,
 						});
 					} else if (block.type === "toolCall") {
-						block.arguments = JSON.parse(block.partialArgs || "{}");
+						block.arguments = parseStreamingJson(block.partialArgs);
 						delete block.partialArgs;
 						stream.push({
 							type: "toolcall_end",
diff --git a/packages/ai/src/providers/openai-responses-shared.ts b/packages/ai/src/providers/openai-responses-shared.ts
index 4642e4e8..552bc606 100644
--- a/packages/ai/src/providers/openai-responses-shared.ts
+++ b/packages/ai/src/providers/openai-responses-shared.ts
@@ -414,8 +414,8 @@ export async function processResponsesStream<TApi extends Api>(
 			} else if (item.type === "function_call") {
 				const args =
 					currentBlock?.type === "toolCall" && currentBlock.partialJson
-						? JSON.parse(currentBlock.partialJson)
-						: JSON.parse(item.arguments);
+						? parseStreamingJson(currentBlock.partialJson)
+						: parseStreamingJson(item.arguments || "{}");
 				const toolCall: ToolCall = {
 					type: "toolCall",
 					id: `${item.call_id}|${item.id}`,