diff --git a/Outputs/CRT/Internals/Shaders/Shader.cpp b/Outputs/CRT/Internals/Shaders/Shader.cpp
index f4968b752..f0e2fbb26 100644
--- a/Outputs/CRT/Internals/Shaders/Shader.cpp
+++ b/Outputs/CRT/Internals/Shaders/Shader.cpp
@@ -291,14 +291,18 @@ void Shader::set_uniform_matrix(const std::string &name, GLint size, GLsizei cou
 
 void Shader::enqueue_function(std::function<void(void)> function)
 {
+	_function_mutex.lock();
 	_enqueued_functions.push_back(function);
+	_function_mutex.unlock();
 }
 
 void Shader::flush_functions()
 {
+	_function_mutex.lock();
 	for(std::function<void(void)> function : _enqueued_functions)
 	{
 		function();
 	}
 	_enqueued_functions.clear();
+	_function_mutex.unlock();
 }
diff --git a/Outputs/CRT/Internals/Shaders/Shader.hpp b/Outputs/CRT/Internals/Shaders/Shader.hpp
index ead7ce397..b28335032 100644
--- a/Outputs/CRT/Internals/Shaders/Shader.hpp
+++ b/Outputs/CRT/Internals/Shaders/Shader.hpp
@@ -13,6 +13,7 @@
 #include <string>
 #include <functional>
 #include <list>
+#include <mutex>
 
 namespace OpenGL {
 
@@ -110,6 +111,7 @@ private:
 
 	void flush_functions();
 	std::list<std::function<void(void)>> _enqueued_functions;
+	std::mutex _function_mutex;
 
 protected:
 	void enqueue_function(std::function<void(void)> function);