diff --git a/source/graphics/TextureConverter.cpp b/source/graphics/TextureConverter.cpp
index 572a051512..237911d410 100644
--- a/source/graphics/TextureConverter.cpp
+++ b/source/graphics/TextureConverter.cpp
@@ -275,10 +275,19 @@ CTextureConverter::CTextureConverter(PIVFS vfs) :
 	// to avoid bugs caused by ABI changes
 	debug_assert(nvtt::version() >= NVTT_VERSION);
 
-	// Start up the worker thread
-	sem_init(&m_WorkerSem, 0, 0);
-	pthread_mutex_init(&m_WorkerMutex, NULL);
-	pthread_create(&m_WorkerThread, NULL, &RunThread, this);
+	// Set up the worker thread:
+
+	int ret;
+
+	// Use SDL semaphores since OS X doesn't implement sem_init
+	m_WorkerSem = SDL_CreateSemaphore(0);
+	debug_assert(m_WorkerSem);
+
+	ret = pthread_mutex_init(&m_WorkerMutex, NULL);
+	debug_assert(ret == 0);
+
+	ret = pthread_create(&m_WorkerThread, NULL, &RunThread, this);
+	debug_assert(ret == 0);
 
 	// Maybe we should share some centralised pool of worker threads?
 	// For now we'll just stick with a single thread for this specific use.
@@ -292,10 +301,14 @@ CTextureConverter::~CTextureConverter()
 	pthread_mutex_unlock(&m_WorkerMutex);
 
 	// Wake it up so it sees the notification
-	sem_post(&m_WorkerSem);
+	SDL_SemPost(m_WorkerSem);
 
 	// Wait for it to shut down cleanly
 	pthread_join(m_WorkerThread, NULL);
+
+	// Clean up resources
+	SDL_DestroySemaphore(m_WorkerSem);
+	pthread_mutex_destroy(&m_WorkerMutex);
 }
 
 bool CTextureConverter::ConvertTexture(const CTexturePtr& texture, const VfsPath& src, const VfsPath& dest, const Settings& settings)
@@ -412,7 +425,7 @@ bool CTextureConverter::ConvertTexture(const CTexturePtr& texture, const VfsPath
 	pthread_mutex_unlock(&m_WorkerMutex);
 
 	// Wake up the worker thread
-	sem_post(&m_WorkerSem);
+	SDL_SemPost(m_WorkerSem);
 
 	return true;
 }
@@ -475,7 +488,7 @@ void* CTextureConverter::RunThread(void* data)
 	CTextureConverter* textureConverter = static_cast<CTextureConverter*>(data);
 
 	// Wait until the main thread wakes us up
-	while (sem_wait(&textureConverter->m_WorkerSem) == 0)
+	while (SDL_SemWait(textureConverter->m_WorkerSem) == 0)
 	{
 		pthread_mutex_lock(&textureConverter->m_WorkerMutex);
 		if (textureConverter->m_Shutdown)
diff --git a/source/graphics/TextureConverter.h b/source/graphics/TextureConverter.h
index e1482f14cf..aebfac8db3 100644
--- a/source/graphics/TextureConverter.h
+++ b/source/graphics/TextureConverter.h
@@ -19,6 +19,7 @@
 #define INCLUDED_TEXTURECONVERTER
 
 #include "lib/file/vfs/vfs.h"
+#include "lib/external_libraries/sdl.h"
 
 #include "TextureManager.h"
 
@@ -201,8 +202,8 @@ private:
 	PIVFS m_VFS;
 
 	pthread_t m_WorkerThread;
-	sem_t m_WorkerSem;
 	pthread_mutex_t m_WorkerMutex;
+	SDL_sem* m_WorkerSem;
 
 	struct ConversionRequest;
 	struct ConversionResult;
diff --git a/source/graphics/TextureManager.cpp b/source/graphics/TextureManager.cpp
index f9a2ffb149..2848ddc517 100644
--- a/source/graphics/TextureManager.cpp
+++ b/source/graphics/TextureManager.cpp
@@ -75,6 +75,7 @@ public:
 		// without needing to load any files
 
 		// Default placeholder texture (grey)
+		if (!m_DisableGL)
 		{
 			// Construct 1x1 24-bit texture
 			shared_ptr<u8> data(new u8[3], ArrayDeleter());
@@ -91,6 +92,7 @@ public:
 		}
 
 		// Error texture (magenta)
+		if (!m_DisableGL)
 		{
 			// Construct 1x1 24-bit texture
 			shared_ptr<u8> data(new u8[3], ArrayDeleter());
@@ -156,6 +158,9 @@ public:
 	 */
 	void LoadTexture(const CTexturePtr& texture, const VfsPath& path)
 	{
+		if (m_DisableGL)
+			return;
+
 		Handle h = ogl_tex_load(m_VFS, path, RES_UNIQUE);
 		if (h <= 0)
 		{
@@ -547,12 +552,14 @@ CTexture::CTexture(Handle handle, const CTextureProperties& props, CTextureManag
 {
 	// Add a reference to the handle (it might be shared by multiple CTextures
 	// so we can't take ownership of it)
-	h_add_ref(m_Handle);
+	if (m_Handle)
+		h_add_ref(m_Handle);
 }
 
 CTexture::~CTexture()
 {
-	ogl_tex_free(m_Handle);
+	if (m_Handle)
+		ogl_tex_free(m_Handle);
 }
 
 void CTexture::Bind(size_t unit)
diff --git a/source/graphics/tests/test_TextureManager.h b/source/graphics/tests/test_TextureManager.h
index 1b97e0ae65..ea9c33ea46 100644
--- a/source/graphics/tests/test_TextureManager.h
+++ b/source/graphics/tests/test_TextureManager.h
@@ -76,8 +76,12 @@ public:
 			}
 
 			TS_ASSERT(t1->IsLoaded());
-			TS_ASSERT_EQUALS(t1->GetWidth(), (size_t)64);
-			TS_ASSERT_EQUALS(t1->GetHeight(), (size_t)64);
+
+			// We can't test sizes because we had to disable GL function calls
+			// and therefore couldn't load the texture. Maybe we should try loading
+			// the texture file directly, to make sure it's actually worked.
+//			TS_ASSERT_EQUALS(t1->GetWidth(), (size_t)64);
+//			TS_ASSERT_EQUALS(t1->GetHeight(), (size_t)64);
 
 			// CreateTexture should return the same object
 			CTexturePtr t2 = texman.CreateTexture(CTextureProperties(L"art/textures/a/demo.png"));