diff --git a/source/simulation2/scripting/EngineScriptConversions.cpp b/source/simulation2/scripting/EngineScriptConversions.cpp
index 02661b21a6..b7f2e28870 100644
--- a/source/simulation2/scripting/EngineScriptConversions.cpp
+++ b/source/simulation2/scripting/EngineScriptConversions.cpp
@@ -253,7 +253,11 @@ template<> void ScriptInterface::ToJSVal<Grid<u8> >(JSContext* cx, JS::MutableHa
 	u32 length = (u32)(val.m_W * val.m_H);
 	u32 nbytes = (u32)(length * sizeof(u8));
 	JS::RootedObject objArr(cx, JS_NewUint8Array(cx, length));
-	memcpy((void*)JS_GetUint8ArrayData(objArr), val.m_Data, nbytes);
+	// Copy the array data and then remove the no-GC check to allow further changes to the JS data
+	{
+		JS::AutoCheckCannotGC nogc;
+		memcpy((void*)JS_GetUint8ArrayData(objArr, nogc), val.m_Data, nbytes);
+	}
 
 	JS::RootedValue data(cx, JS::ObjectValue(*objArr));
 	JS::RootedValue w(cx);
@@ -275,7 +279,11 @@ template<> void ScriptInterface::ToJSVal<Grid<u16> >(JSContext* cx, JS::MutableH
 	u32 length = (u32)(val.m_W * val.m_H);
 	u32 nbytes = (u32)(length * sizeof(u16));
 	JS::RootedObject objArr(cx, JS_NewUint16Array(cx, length));
-	memcpy((void*)JS_GetUint16ArrayData(objArr), val.m_Data, nbytes);
+	// Copy the array data and then remove the no-GC check to allow further changes to the JS data
+	{
+		JS::AutoCheckCannotGC nogc;
+		memcpy((void*)JS_GetUint16ArrayData(objArr, nogc), val.m_Data, nbytes);
+	}
  
 	JS::RootedValue data(cx, JS::ObjectValue(*objArr));
 	JS::RootedValue w(cx);