diff --git a/source/gui/ObjectBases/IGUIObject.cpp b/source/gui/ObjectBases/IGUIObject.cpp
index 8653452d5d..24cbfc9022 100644
--- a/source/gui/ObjectBases/IGUIObject.cpp
+++ b/source/gui/ObjectBases/IGUIObject.cpp
@@ -315,6 +315,7 @@ void IGUIObject::RegisterScriptHandler(const CStr& eventName, const CStr& Code,
 	JS::CompileOptions options(rq.cx);
 	options.setFileAndLine(CodeName.c_str(), 0);
 	options.setIsRunOnce(false);
+	options.setForceStrictMode();
 
 	JS::SourceText<mozilla::Utf8Unit> src;
 	ENSURE(src.init(rq.cx, Code.c_str(), Code.length(), JS::SourceOwnership::Borrowed));
diff --git a/source/scriptinterface/ScriptContext.cpp b/source/scriptinterface/ScriptContext.cpp
index c0c814e03d..8274e76cc6 100644
--- a/source/scriptinterface/ScriptContext.cpp
+++ b/source/scriptinterface/ScriptContext.cpp
@@ -127,8 +127,6 @@ ScriptContext::ScriptContext(int contextSize, int heapGrowthBytesGCTrigger):
 	JS_SetGlobalJitCompilerOption(m_cx, JSJITCOMPILER_SPECTRE_STRING_MITIGATIONS, 0);
 	JS_SetGlobalJitCompilerOption(m_cx, JSJITCOMPILER_SPECTRE_OBJECT_MITIGATIONS, 0);
 
-	JS::ContextOptionsRef(m_cx).setStrictMode(true);
-
 	ScriptEngine::GetSingleton().RegisterContext(m_cx);
 
 	JS::SetJobQueue(m_cx, m_JobQueue.get());
diff --git a/source/scriptinterface/ScriptInterface.cpp b/source/scriptinterface/ScriptInterface.cpp
index aa93a2fd8d..1d62a8a78b 100644
--- a/source/scriptinterface/ScriptInterface.cpp
+++ b/source/scriptinterface/ScriptInterface.cpp
@@ -626,6 +626,7 @@ bool ScriptInterface::LoadScript(const VfsPath& filename, const std::string& cod
 	// TODO: it would probably be better to not implicitly introduce JS scopes.
 	options.setFileAndLine(filenameStr.c_str(), 0);
 	options.setIsRunOnce(false);
+	options.setForceStrictMode();
 
 	JS::SourceText<mozilla::Utf8Unit> src;
 	ENSURE(src.init(rq.cx, code.c_str(), code.length(), JS::SourceOwnership::Borrowed));
@@ -655,6 +656,7 @@ bool ScriptInterface::LoadGlobalScript(const VfsPath& filename, const std::strin
 	JS::RootedValue rval(rq.cx);
 	JS::CompileOptions opts(rq.cx);
 	opts.setFileAndLine(filenameStr.c_str(), 1);
+	opts.setForceStrictMode();
 
 	JS::SourceText<mozilla::Utf8Unit> src;
 	ENSURE(src.init(rq.cx, code.c_str(), code.length(), JS::SourceOwnership::Borrowed));
@@ -695,6 +697,7 @@ bool ScriptInterface::Eval(const char* code) const
 
 	JS::CompileOptions opts(rq.cx);
 	opts.setFileAndLine("(eval)", 1);
+	opts.setForceStrictMode();
 	JS::SourceText<mozilla::Utf8Unit> src;
 	ENSURE(src.init(rq.cx, code, strlen(code), JS::SourceOwnership::Borrowed));
 	if (JS::Evaluate(rq.cx, opts, src, &rval))
@@ -710,6 +713,7 @@ bool ScriptInterface::Eval(const char* code, JS::MutableHandleValue rval) const
 
 	JS::CompileOptions opts(rq.cx);
 	opts.setFileAndLine("(eval)", 1);
+	opts.setForceStrictMode();
 	JS::SourceText<mozilla::Utf8Unit> src;
 	ENSURE(src.init(rq.cx, code, strlen(code), JS::SourceOwnership::Borrowed));
 	if (JS::Evaluate(rq.cx, opts, src, rval))