diff --git a/GUI/extenwindow.cpp b/GUI/extenwindow.cpp
index eee5402..7960aeb 100644
--- a/GUI/extenwindow.cpp
+++ b/GUI/extenwindow.cpp
@@ -4,7 +4,6 @@
 #include "text.h"
 #include "types.h"
 #include "misc.h"
-#include <shared_mutex>
 #include <QDragEnterEvent>
 #include <QDropEvent>
 #include <QMimeData>
@@ -21,7 +20,7 @@ namespace
 		~InfoForExtension() { if (next) delete next; };
 	};
 
-	QHash<QString, wchar_t*(*)(const wchar_t*, const InfoForExtension*)> extensions;
+	QHash<QString, wchar_t*(*)(wchar_t*, const InfoForExtension*)> extensions;
 	QStringList extenNames;
 	std::shared_mutex extenMutex;
 
@@ -32,7 +31,7 @@ namespace
 		if (FARPROC callback = GetProcAddress(LoadLibraryOnce(S(extenName)), "OnNewSentence"))
 		{
 			std::scoped_lock writeLock(extenMutex);
-			extensions[extenName] = (wchar_t*(*)(const wchar_t*, const InfoForExtension*))callback;
+			extensions[extenName] = (wchar_t*(*)(wchar_t*, const InfoForExtension*))callback;
 			extenNames.push_back(extenName);
 		}
 	}
diff --git a/GUI/host/textthread.cpp b/GUI/host/textthread.cpp
index 118ac99..7a71b31 100644
--- a/GUI/host/textthread.cpp
+++ b/GUI/host/textthread.cpp
@@ -46,7 +46,7 @@ void TextThread::Flush()
 {
 	std::vector<std::wstring> sentences;
 	queuedSentences->swap(sentences);
-	for (auto sentence : sentences)
+	for (auto& sentence : sentences)
 		if (Output(this, sentence)) storage->append(sentence);
 
 	std::scoped_lock lock(bufferMutex);
diff --git a/extensions/extensionimpl.cpp b/extensions/extensionimpl.cpp
index 794d91b..f84ee35 100644
--- a/extensions/extensionimpl.cpp
+++ b/extensions/extensionimpl.cpp
@@ -13,15 +13,16 @@ bool ProcessSentence(std::wstring& sentence, SentenceInfo sentenceInfo);
 	* Textractor will display the sentence after all extensions have had a chance to process and/or modify it.
 	* THIS FUNCTION MAY BE RUN SEVERAL TIMES CONCURRENTLY: PLEASE ENSURE THAT IT IS THREAD SAFE!
 */
-extern "C" __declspec(dllexport) const wchar_t* OnNewSentence(const wchar_t* sentence, const InfoForExtension* miscInfo)
+extern "C" __declspec(dllexport) wchar_t* OnNewSentence(wchar_t* sentence, const InfoForExtension* miscInfo)
 {
 	try
 	{
 		std::wstring sentenceStr(sentence);
+		int origLength = sentenceStr.size();
 		if (ProcessSentence(sentenceStr, SentenceInfo{ miscInfo }))
 		{
 			// No need to worry about freeing this: Textractor does it for you.
-			wchar_t* newSentence = (wchar_t*)HeapAlloc(GetProcessHeap(), 0, (sentenceStr.size() + 1) * sizeof(wchar_t));
+			wchar_t* newSentence = sentenceStr.size() > origLength ? (wchar_t*)HeapAlloc(GetProcessHeap(), 0, (sentenceStr.size() + 1) * sizeof(wchar_t)) : sentence;
 			wcscpy_s(newSentence, sentenceStr.size() + 1, sentenceStr.c_str());
 			return newSentence;
 		}
diff --git a/extensions/regexfilter.cpp b/extensions/regexfilter.cpp
index f4d2734..57eda59 100644
--- a/extensions/regexfilter.cpp
+++ b/extensions/regexfilter.cpp
@@ -7,7 +7,7 @@
 #include <QTimer>
 
 std::wregex regex;
-std::mutex m;
+std::shared_mutex m;
 
 struct : QMainWindow 
 {
@@ -63,7 +63,7 @@ BOOL WINAPI DllMain(HMODULE hModule, DWORD ul_reason_for_call, LPVOID lpReserved
 
 bool ProcessSentence(std::wstring& sentence, SentenceInfo sentenceInfo)
 {
-	std::lock_guard l(m);
+	std::shared_lock l(m);
 	if (window == nullptr || sentenceInfo["hook address"] == -1) return false;
 	sentence = std::regex_replace(sentence, regex, L"");
 	return true;
diff --git a/include/common.h b/include/common.h
index f648c4a..3f8e5f1 100644
--- a/include/common.h
+++ b/include/common.h
@@ -13,5 +13,6 @@
 #include <optional>
 #include <thread>
 #include <mutex>
+#include <shared_mutex>
 #include <cstdint>
 #include <cassert>