diff --git a/extern/shiny/Main/Factory.cpp b/extern/shiny/Main/Factory.cpp
index 82d664811..c63a9e367 100644
--- a/extern/shiny/Main/Factory.cpp
+++ b/extern/shiny/Main/Factory.cpp
@@ -191,15 +191,48 @@ namespace sh
 								  &mGlobalSettings);
 
 				int lastModified = boost::filesystem::last_write_time (boost::filesystem::path(sourceFile));
+				mShadersLastModifiedNew[sourceFile] = lastModified;
 				if (mShadersLastModified.find(sourceFile) != mShadersLastModified.end()
 						&& mShadersLastModified[sourceFile] != lastModified)
 				{
-					newSet.markDirty ();
+					// delete any outdated shaders based on this shader set.
+					if ( boost::filesystem::exists(mPlatform->getCacheFolder())
+						 && boost::filesystem::is_directory(mPlatform->getCacheFolder()))
+					{
+						boost::filesystem::directory_iterator end_iter;
+						for( boost::filesystem::directory_iterator dir_iter(mPlatform->getCacheFolder()) ; dir_iter != end_iter ; ++dir_iter)
+						{
+							if (boost::filesystem::is_regular_file(dir_iter->status()) )
+							{
+								boost::filesystem::path file = dir_iter->path();
+
+								std::string pathname = file.filename().string();
+
+								// get first part of filename, e.g. main_fragment_546457654 -> main_fragment
+								// there is probably a better method for this...
+								std::vector<std::string> tokens;
+								boost::split(tokens, pathname, boost::is_any_of("_"));
+								tokens.erase(--tokens.end());
+								std::string shaderName;
+								for (std::vector<std::string>::const_iterator vector_iter = tokens.begin(); vector_iter != tokens.end();)
+								{
+									shaderName += *(vector_iter++);
+									if (vector_iter != tokens.end())
+										shaderName += "_";
+								}
+
+								if (shaderName == it->first)
+								{
+									boost::filesystem::remove(file);
+									std::cout << "Removing outdated file: " << file << std::endl;
+								}
+							}
+						}
+					}
+
 					anyShaderDirty = true;
 				}
 
-				mShadersLastModified[sourceFile] = lastModified;
-
 				mShaderSets.insert(std::make_pair(it->first, newSet));
 			}
 		}
@@ -313,11 +346,11 @@ namespace sh
 
 		if (mReadSourceCache)
 		{
-			// save the last modified time of shader sources
+			// save the last modified time of shader sources (as of when they were loaded)
 			std::ofstream file;
 			file.open(std::string(mPlatform->getCacheFolder () + "/lastModified.txt").c_str());
 
-			for (LastModifiedMap::const_iterator it = mShadersLastModified.begin(); it != mShadersLastModified.end(); ++it)
+			for (LastModifiedMap::const_iterator it = mShadersLastModifiedNew.begin(); it != mShadersLastModifiedNew.end(); ++it)
 			{
 				file << it->first << "\n" << it->second << std::endl;
 			}
diff --git a/extern/shiny/Main/Factory.hpp b/extern/shiny/Main/Factory.hpp
index 799dd71eb..1062c079c 100644
--- a/extern/shiny/Main/Factory.hpp
+++ b/extern/shiny/Main/Factory.hpp
@@ -185,6 +185,7 @@ namespace sh
 		ConfigurationMap mConfigurations;
 		LodConfigurationMap mLodConfigurations;
 		LastModifiedMap mShadersLastModified;
+		LastModifiedMap mShadersLastModifiedNew;
 
 		PropertySetGet mGlobalSettings;
 
diff --git a/extern/shiny/Main/ShaderInstance.cpp b/extern/shiny/Main/ShaderInstance.cpp
index 0e074c7b4..1539128ab 100644
--- a/extern/shiny/Main/ShaderInstance.cpp
+++ b/extern/shiny/Main/ShaderInstance.cpp
@@ -337,8 +337,7 @@ namespace sh
 		size_t pos;
 
 		bool readCache = Factory::getInstance ().getReadSourceCache () && boost::filesystem::exists(
-					Factory::getInstance ().getCacheFolder () + "/" + mName)
-				&& !mParent->isDirty ();
+					Factory::getInstance ().getCacheFolder () + "/" + mName);
 		bool writeCache = Factory::getInstance ().getWriteSourceCache ();
 
 
@@ -363,12 +362,6 @@ namespace sh
 
 			if (Factory::getInstance ().getShaderDebugOutputEnabled ())
 				writeDebugFile(source, name + ".pre");
-            else
-            {
-    #ifdef SHINY_WRITE_SHADER_DEBUG
-                writeDebugFile(source, name + ".pre");
-    #endif
-            }
 
 			// why do we need our own preprocessor? there are several custom commands available in the shader files
 			// (for example for binding uniforms to properties or auto constants) - more below. it is important that these
@@ -648,12 +641,6 @@ namespace sh
 
 		if (Factory::getInstance ().getShaderDebugOutputEnabled ())
 			writeDebugFile(source, name);
-        else
-        {
-#ifdef SHINY_WRITE_SHADER_DEBUG
-            writeDebugFile(source, name);
-#endif
-        }
 
 		if (!mProgram->getSupported())
 		{
diff --git a/extern/shiny/Main/ShaderSet.cpp b/extern/shiny/Main/ShaderSet.cpp
index 2702ece19..413d7d1a2 100644
--- a/extern/shiny/Main/ShaderSet.cpp
+++ b/extern/shiny/Main/ShaderSet.cpp
@@ -17,7 +17,6 @@ namespace sh
 		, mName(name)
 		, mCgProfile(cgProfile)
 		, mHlslProfile(hlslProfile)
-		, mIsDirty(false)
 	{
 		if (type == "vertex")
 			mType = GPT_Vertex;
diff --git a/extern/shiny/Main/ShaderSet.hpp b/extern/shiny/Main/ShaderSet.hpp
index 776750598..a423b6779 100644
--- a/extern/shiny/Main/ShaderSet.hpp
+++ b/extern/shiny/Main/ShaderSet.hpp
@@ -30,9 +30,6 @@ namespace sh
 		/// so it does not matter if you pass any extra properties that the shader does not care about.
 		ShaderInstance* getInstance (PropertySetGet* properties);
 
-		void markDirty() { mIsDirty = true; }
-		///< Signals that the cache is out of date, and thus should not be used this time
-
 	private:
 		PropertySetGet* getCurrentGlobalSettings() const;
 		std::string getBasePath() const;
@@ -41,12 +38,8 @@ namespace sh
 		std::string getHlslProfile() const;
 		int getType() const;
 
-		bool isDirty() { return mIsDirty; }
-
 		friend class ShaderInstance;
 
-		bool mIsDirty;
-
 	private:
 		GpuProgramType mType;
 		std::string mSource;