diff --git a/IDEHelper/Compiler/BfCompiler.cpp b/IDEHelper/Compiler/BfCompiler.cpp
index d0525cc0..0a00f353 100644
--- a/IDEHelper/Compiler/BfCompiler.cpp
+++ b/IDEHelper/Compiler/BfCompiler.cpp
@@ -487,7 +487,7 @@ BfCompiler::BfCompiler(BfSystem* bfSystem, bool isResolveOnly)
 }
 
 BfCompiler::~BfCompiler()
-{		
+{
 	delete mCeMachine;
 	mCeMachine = NULL;
 	delete mContext;
@@ -895,6 +895,7 @@ void BfCompiler::GetTestMethods(BfVDataModule* bfModule, Array<TestMethod>& test
 		testMethod.mMethodInstance = methodInstance;
 		testMethods.Add(testMethod);
 
+		BF_ASSERT_REL(!typeInstance->mModule->mIsDeleting);
 		if (!bfModule->mProject->mUsedModules.Contains(typeInstance->mModule))
 		{
 			bfModule->mProject->mUsedModules.Add(typeInstance->mModule);
@@ -1077,6 +1078,7 @@ void BfCompiler::CreateVData(BfVDataModule* bfModule)
 	BfLogSysM("CreateVData %s\n", bfModule->mProject->mName.c_str());
 	CompileLog("CreateVData %s\n", bfModule->mProject->mName.c_str());
 	
+	BF_ASSERT_REL(!bfModule->mIsDeleting);
 	bfModule->mProject->mUsedModules.Add(bfModule);
 
 	auto project = bfModule->mProject;
@@ -7609,7 +7611,7 @@ bool BfCompiler::DoCompile(const StringImpl& outputDirectory)
 
 						if (bfModule->mParentModule != NULL)
 						{
-							for (auto&& fileName : bfModule->mOutFileNames)
+							for (auto& fileName : bfModule->mOutFileNames)
 							{
 								if (!mainModule->mOutFileNames.Contains(fileName))
 									mainModule->mOutFileNames.push_back(fileName);
@@ -7704,7 +7706,7 @@ bool BfCompiler::DoCompile(const StringImpl& outputDirectory)
 				BfModule* bfModule = mainModule;
 				if (bfModule->mIsReified)
 				{
-					for (auto outFileName : bfModule->mOutFileNames)
+					for (auto& outFileName : bfModule->mOutFileNames)
 					{
 						if (outFileName.mModuleWritten)
 							BeLibManager::Get()->AddUsedFileName(outFileName.mFileName);
@@ -10473,9 +10475,12 @@ BF_EXPORT const char* BF_CALLTYPE BfCompiler_GetUsedOutputFileNames(BfCompiler*
 	HashSet<String> usedFileNames;
 	usedFileNames.Reserve(moduleList.size());
 
-	for (auto mainModule : moduleList)
+	//for (auto mainModule : moduleList)
+	for (int i = 0; i < moduleList.mSize; i++)
 	{
-		BF_ASSERT(!mainModule->mIsDeleting);
+		auto mainModule = moduleList[i];
+		BF_ASSERT_REL(!mainModule->mIsDeleting);
+		BF_ASSERT_REL((mainModule->mRevision > -2) && (mainModule->mRevision < 1000000));
 
 		if ((flags & BfUsedOutputFlags_SkipImports) == 0)
 		{
@@ -10490,7 +10495,7 @@ BF_EXPORT const char* BF_CALLTYPE BfCompiler_GetUsedOutputFileNames(BfCompiler*
 			}
 		}
 
-		for (auto&& moduleFileName : mainModule->mOutFileNames)
+		for (auto& moduleFileName : mainModule->mOutFileNames)
 		{
 			if (!moduleFileName.mModuleWritten)
 				continue;
diff --git a/IDEHelper/Compiler/BfContext.cpp b/IDEHelper/Compiler/BfContext.cpp
index ccfb931b..2d42dce8 100644
--- a/IDEHelper/Compiler/BfContext.cpp
+++ b/IDEHelper/Compiler/BfContext.cpp
@@ -1798,7 +1798,7 @@ void BfContext::DeleteType(BfType* type, bool deferDepRebuilds)
 					
 					// This was only needed for 'zombie modules', which we don't need anymore?
 					//  To avoid linking errors.  Used instead of directly removing from mModules.
-					mDeletingModules.push_back(module);
+					mDeletingModules.Add(module);
 				}
 			}
 		}
@@ -3187,7 +3187,7 @@ void BfContext::MarkUsedModules(BfProject* project, BfModule* module)
 {
 	BP_ZONE("BfContext::MarkUsedModules");
 
-	BF_ASSERT(!module->mIsDeleting);
+	BF_ASSERT_REL(!module->mIsDeleting);
 
 	if (module->mIsScratchModule)
 		return;
@@ -3316,10 +3316,15 @@ void BfContext::Cleanup()
 		{
 			for (auto itr = project->mUsedModules.begin(); itr != project->mUsedModules.end(); )
 			{
-				if ((*itr)->mIsDeleting)
+				auto module = *itr;
+				
+				if (module->mIsDeleting)
 					itr = project->mUsedModules.Remove(itr);
 				else
+				{
+					BF_ASSERT_REL(module->mRevision > -2);
 					++itr;
+				}
 			}
 		}
 	}
diff --git a/IDEHelper/Compiler/BfModule.cpp b/IDEHelper/Compiler/BfModule.cpp
index 8d097649..d350a5be 100644
--- a/IDEHelper/Compiler/BfModule.cpp
+++ b/IDEHelper/Compiler/BfModule.cpp
@@ -930,6 +930,8 @@ void BfReportMemory();
 
 BfModule::~BfModule()
 {	
+	mRevision = -2;
+
 	BfLogSysM("Deleting module %p: %s \n", this, mModuleName.c_str());
 
 	if (!mIsDeleting)
@@ -1311,7 +1313,13 @@ void BfModule::StartNewRevision(RebuildKind rebuildKind, bool force)
 		for (auto& specPair : mSpecializedMethodModules)
 		{
 			auto specModule = specPair.mValue;
-			delete specModule;
+
+			BfLogSysM("Setting module mIsDeleting %p due to parent module starting a new revision\n", module);
+
+			// This module is no longer needed
+			specModule->RemoveModuleData();
+			specModule->mIsDeleting = true;
+			mContext->mDeletingModules.Add(specModule);
 		}
 	}
 	mSpecializedMethodModules.Clear();