diff --git a/packages/xsnap/src/xsnap.c b/packages/xsnap/src/xsnap.c
index 277bec2c213..4e33b97c20c 100644
--- a/packages/xsnap/src/xsnap.c
+++ b/packages/xsnap/src/xsnap.c
@@ -1389,10 +1389,12 @@ static int fxReadNetString(FILE *inStream, char** dest, size_t* len)
 		} else {
 			*(buf + *len) = 0;
 		}
-		if (code != 0) {
+		if (code == 0) {
+			*dest = buf;
+		} else {
+			*dest = 0;
 			free(buf);
 		}
-		*dest = buf;
 	}
 	return code;
 }
@@ -1473,12 +1475,14 @@ static void fx_issueCommand(xsMachine *the)
 
 	size_t length;
 	char* buf = NULL;
-	txSlot* arrayBuffer = &xsArg(0);
-	length = fxGetArrayBufferLength(the, arrayBuffer);
+	length = xsGetArrayBufferLength(xsArg(0));
 
 	buf = malloc(length);
+	if (!buf) {
+		fxAbort(the, XS_NOT_ENOUGH_MEMORY_EXIT);
+	}
 
-	fxGetArrayBufferData(the, arrayBuffer, 0, buf, length);
+	xsGetArrayBufferData(xsArg(0), 0, buf, length);
 	int writeError = fxWriteNetString(toParent, "?", buf, length);
 
 	free(buf);
@@ -1495,6 +1499,7 @@ static void fx_issueCommand(xsMachine *the)
 	}
 
 	xsResult = xsArrayBuffer(buf, len);
+	free(buf);
 }
 
 
diff --git a/packages/xsnap/test/test-xs-perf.js b/packages/xsnap/test/test-xs-perf.js
index ff442e72887..9cf903bad51 100644
--- a/packages/xsnap/test/test-xs-perf.js
+++ b/packages/xsnap/test/test-xs-perf.js
@@ -1,7 +1,27 @@
 // eslint-disable-next-line import/no-extraneous-dependencies
 import test from 'ava';
+import * as childProcess from 'child_process';
+import * as os from 'os';
 import { xsnap } from '../src/xsnap';
-import { options } from './test-xsnap';
+
+const decoder = new TextDecoder();
+
+const xsnapOptions = {
+  name: 'xsnap test worker',
+  spawn: childProcess.spawn,
+  os: os.type(),
+  stderr: 'inherit',
+  stdout: 'inherit',
+};
+
+export function options() {
+  const messages = [];
+  async function handleCommand(message) {
+    messages.push(decoder.decode(message));
+    return new Uint8Array();
+  }
+  return { ...xsnapOptions, handleCommand, messages };
+}
 
 test('meter details', async t => {
   const opts = options();