diff --git a/CHANGES b/CHANGES
index 372317221..b3a97384f 100644
--- a/CHANGES
+++ b/CHANGES
@@ -5,6 +5,7 @@ Features:
  - Booting of multiboot images
  - Customization of GIF recording
  - Libretro: Cheat code support
+ - Support for GLSL shaders
 Bugfixes:
  - Util: Fix PowerPC PNG read/write pixel order
  - Qt: Use safer isLoaded check in GameController
diff --git a/src/platform/opengl/gles2.c b/src/platform/opengl/gles2.c
index 40a43becf..0fcea3f0f 100644
--- a/src/platform/opengl/gles2.c
+++ b/src/platform/opengl/gles2.c
@@ -84,18 +84,35 @@ static void GBAGLES2ContextInit(struct VideoBackend* v, WHandle handle) {
 
 	struct GBAGLES2Uniform* uniforms = malloc(sizeof(struct GBAGLES2Uniform) * 3);
 	uniforms[0].name = "gamma";
+	uniforms[0].readableName = "Gamma";
 	uniforms[0].type = GL_FLOAT;
 	uniforms[0].value.f = 1.0f;
+	uniforms[0].min.f = 0.1f;
+	uniforms[0].max.f = 3.0f;
 	uniforms[1].name = "scale";
+	uniforms[1].readableName = "Scale";
 	uniforms[1].type = GL_FLOAT_VEC3;
 	uniforms[1].value.fvec3[0] = 1.0f;
 	uniforms[1].value.fvec3[1] = 1.0f;
 	uniforms[1].value.fvec3[2] = 1.0f;
+	uniforms[1].min.fvec3[0] = -1.0f;
+	uniforms[1].min.fvec3[1] = -1.0f;
+	uniforms[1].min.fvec3[2] = -1.0f;
+	uniforms[1].max.fvec3[0] = 2.0f;
+	uniforms[1].max.fvec3[1] = 2.0f;
+	uniforms[1].max.fvec3[2] = 2.0f;
 	uniforms[2].name = "bias";
+	uniforms[2].readableName = "Bias";
 	uniforms[2].type = GL_FLOAT_VEC3;
 	uniforms[2].value.fvec3[0] = 0.0f;
 	uniforms[2].value.fvec3[1] = 0.0f;
 	uniforms[2].value.fvec3[2] = 0.0f;
+	uniforms[2].min.fvec3[0] = -1.0f;
+	uniforms[2].min.fvec3[1] = -1.0f;
+	uniforms[2].min.fvec3[2] = -1.0f;
+	uniforms[2].max.fvec3[0] = 1.0f;
+	uniforms[2].max.fvec3[1] = 1.0f;
+	uniforms[2].max.fvec3[2] = 1.0f;
 	GBAGLES2ShaderInit(&context->initialShader, _vertexShader, _fragmentShader, -1, -1, uniforms, 3);
 	GBAGLES2ShaderInit(&context->finalShader, 0, 0, 0, 0, 0, 0);
 	glDeleteFramebuffers(1, &context->finalShader.fbo);
diff --git a/src/platform/qt/DisplayGL.cpp b/src/platform/qt/DisplayGL.cpp
index d755d6c0e..655cf2f07 100644
--- a/src/platform/qt/DisplayGL.cpp
+++ b/src/platform/qt/DisplayGL.cpp
@@ -208,6 +208,19 @@ PainterGL::PainterGL(QGLWidget* parent, QGLFormat::OpenGLVersionFlags glVersion)
 		PainterGL* painter = static_cast<PainterGL*>(v->user);
 		painter->m_gl->swapBuffers();
 	};
+
+	m_gl->makeCurrent();
+#if defined(_WIN32) && defined(USE_EPOXY)
+	epoxy_handle_external_wglMakeCurrent();
+#endif
+	m_backend->init(m_backend, reinterpret_cast<WHandle>(m_gl->winId()));
+#if !defined(_WIN32) || defined(USE_EPOXY)
+	if (m_supportsShaders) {
+		m_shader.preprocessShader = static_cast<void*>(&reinterpret_cast<GBAGLES2Context*>(m_backend)->initialShader);
+	}
+#endif
+	m_gl->doneCurrent();
+
 	m_backend->user = this;
 	m_backend->filter = false;
 	m_backend->lockAspectRatio = false;
@@ -224,11 +237,14 @@ PainterGL::~PainterGL() {
 	for (auto item : m_free) {
 		delete[] item;
 	}
-	delete m_backend;
-	m_backend = nullptr;
+#if !defined(_WIN32) || defined(USE_EPOXY)
 	if (m_shader.passes) {
 		GBAGLES2ShaderFree(&m_shader);
 	}
+#endif
+	m_backend->deinit(m_backend);
+	delete m_backend;
+	m_backend = nullptr;
 }
 
 void PainterGL::setContext(GBAThread* context) {
@@ -265,10 +281,9 @@ void PainterGL::start() {
 #if defined(_WIN32) && defined(USE_EPOXY)
 	epoxy_handle_external_wglMakeCurrent();
 #endif
-	m_backend->init(m_backend, reinterpret_cast<WHandle>(m_gl->winId()));
 
 #if !defined(_WIN32) || defined(USE_EPOXY)
-	if (m_shader.passes) {
+	if (m_supportsShaders && m_shader.passes) {
 		GBAGLES2ShaderAttach(reinterpret_cast<GBAGLES2Context*>(m_backend), static_cast<GBAGLES2Shader*>(m_shader.passes), m_shader.nPasses);
 	}
 #endif
@@ -314,7 +329,6 @@ void PainterGL::stop() {
 	dequeueAll();
 	m_backend->clear(m_backend);
 	m_backend->swap(m_backend);
-	m_backend->deinit(m_backend);
 	m_gl->doneCurrent();
 	m_gl->context()->moveToThread(m_gl->thread());
 	moveToThread(m_gl->thread());
diff --git a/src/platform/qt/ShaderSelector.cpp b/src/platform/qt/ShaderSelector.cpp
index 34d66ffa1..17dbbf49e 100644
--- a/src/platform/qt/ShaderSelector.cpp
+++ b/src/platform/qt/ShaderSelector.cpp
@@ -106,55 +106,13 @@ void ShaderSelector::refreshShaders() {
 	}
 
 #if !defined(_WIN32) || defined(USE_EPOXY)
+	m_ui.passes->addTab(makePage(static_cast<GBAGLES2Shader*>(m_shaders->preprocessShader)), tr("Preprocessing"));
 	GBAGLES2Shader* shaders = static_cast<GBAGLES2Shader*>(m_shaders->passes);
 	for (size_t p = 0; p < m_shaders->nPasses; ++p) {
-		QWidget* page = new QWidget;
-		QFormLayout* layout = new QFormLayout;
-		page->setLayout(layout);
-		for (size_t u = 0 ; u < shaders[p].nUniforms; ++u) {
-			QGridLayout* settings = new QGridLayout;
-			GBAGLES2Uniform* uniform = &shaders[p].uniforms[u];
-			switch (uniform->type) {
-			case GL_FLOAT:
-				addUniform(settings, &uniform->value.f, uniform->min.f, uniform->max.f, 0, 0);
-				break;
-			case GL_FLOAT_VEC2:
-				addUniform(settings, &uniform->value.fvec2[0], uniform->min.fvec2[0], uniform->max.fvec2[0], 0, 0);
-				addUniform(settings, &uniform->value.fvec2[1], uniform->min.fvec2[1], uniform->max.fvec2[1], 0, 1);
-				break;
-			case GL_FLOAT_VEC3:
-				addUniform(settings, &uniform->value.fvec3[0], uniform->min.fvec3[0], uniform->max.fvec3[0], 0, 0);
-				addUniform(settings, &uniform->value.fvec3[1], uniform->min.fvec3[1], uniform->max.fvec3[1], 0, 1);
-				addUniform(settings, &uniform->value.fvec3[2], uniform->min.fvec3[2], uniform->max.fvec3[2], 0, 2);
-				break;
-			case GL_FLOAT_VEC4:
-				addUniform(settings, &uniform->value.fvec4[0], uniform->min.fvec4[0], uniform->max.fvec4[0], 0, 0);
-				addUniform(settings, &uniform->value.fvec4[1], uniform->min.fvec4[1], uniform->max.fvec4[1], 0, 1);
-				addUniform(settings, &uniform->value.fvec4[2], uniform->min.fvec4[2], uniform->max.fvec4[2], 0, 2);
-				addUniform(settings, &uniform->value.fvec4[3], uniform->min.fvec4[3], uniform->max.fvec4[3], 0, 3);
-				break;
-			case GL_INT:
-				addUniform(settings, &uniform->value.i, uniform->min.i, uniform->max.i, 0, 0);
-				break;
-			case GL_INT_VEC2:
-				addUniform(settings, &uniform->value.ivec2[0], uniform->min.ivec2[0], uniform->max.ivec2[0], 0, 0);
-				addUniform(settings, &uniform->value.ivec2[1], uniform->min.ivec2[1], uniform->max.ivec2[1], 0, 1);
-				break;
-			case GL_INT_VEC3:
-				addUniform(settings, &uniform->value.ivec3[0], uniform->min.ivec3[0], uniform->max.ivec3[0], 0, 0);
-				addUniform(settings, &uniform->value.ivec3[1], uniform->min.ivec3[1], uniform->max.ivec3[1], 0, 1);
-				addUniform(settings, &uniform->value.ivec3[2], uniform->min.ivec3[2], uniform->max.ivec3[2], 0, 2);
-				break;
-			case GL_INT_VEC4:
-				addUniform(settings, &uniform->value.ivec4[0], uniform->min.ivec4[0], uniform->max.ivec4[0], 0, 0);
-				addUniform(settings, &uniform->value.ivec4[1], uniform->min.ivec4[1], uniform->max.ivec4[1], 0, 1);
-				addUniform(settings, &uniform->value.ivec4[2], uniform->min.ivec4[2], uniform->max.ivec4[2], 0, 2);
-				addUniform(settings, &uniform->value.ivec4[3], uniform->min.ivec4[3], uniform->max.ivec4[3], 0, 3);
-				break;
-			}
-			layout->addRow(shaders[p].uniforms[u].readableName, settings);
+		QWidget* page = makePage(&shaders[p]);
+		if (page) {
+			m_ui.passes->addTab(page, tr("Pass %1").arg(p + 1));
 		}
-		m_ui.passes->addTab(page, tr("Pass %1").arg(p + 1));
 	}
 #endif
 }
@@ -191,3 +149,56 @@ void ShaderSelector::addUniform(QGridLayout* settings, int* value, int min, int
 		// TODO: Config
 	});
 }
+
+QWidget* ShaderSelector::makePage(GBAGLES2Shader* shader) {
+	if (!shader->nUniforms) {
+		return nullptr;
+	}
+	QWidget* page = new QWidget;
+	QFormLayout* layout = new QFormLayout;
+	page->setLayout(layout);
+	for (size_t u = 0 ; u < shader->nUniforms; ++u) {
+		QGridLayout* settings = new QGridLayout;
+		GBAGLES2Uniform* uniform = &shader->uniforms[u];
+		switch (uniform->type) {
+		case GL_FLOAT:
+			addUniform(settings, &uniform->value.f, uniform->min.f, uniform->max.f, 0, 0);
+			break;
+		case GL_FLOAT_VEC2:
+			addUniform(settings, &uniform->value.fvec2[0], uniform->min.fvec2[0], uniform->max.fvec2[0], 0, 0);
+			addUniform(settings, &uniform->value.fvec2[1], uniform->min.fvec2[1], uniform->max.fvec2[1], 0, 1);
+			break;
+		case GL_FLOAT_VEC3:
+			addUniform(settings, &uniform->value.fvec3[0], uniform->min.fvec3[0], uniform->max.fvec3[0], 0, 0);
+			addUniform(settings, &uniform->value.fvec3[1], uniform->min.fvec3[1], uniform->max.fvec3[1], 0, 1);
+			addUniform(settings, &uniform->value.fvec3[2], uniform->min.fvec3[2], uniform->max.fvec3[2], 0, 2);
+			break;
+		case GL_FLOAT_VEC4:
+			addUniform(settings, &uniform->value.fvec4[0], uniform->min.fvec4[0], uniform->max.fvec4[0], 0, 0);
+			addUniform(settings, &uniform->value.fvec4[1], uniform->min.fvec4[1], uniform->max.fvec4[1], 0, 1);
+			addUniform(settings, &uniform->value.fvec4[2], uniform->min.fvec4[2], uniform->max.fvec4[2], 0, 2);
+			addUniform(settings, &uniform->value.fvec4[3], uniform->min.fvec4[3], uniform->max.fvec4[3], 0, 3);
+			break;
+		case GL_INT:
+			addUniform(settings, &uniform->value.i, uniform->min.i, uniform->max.i, 0, 0);
+			break;
+		case GL_INT_VEC2:
+			addUniform(settings, &uniform->value.ivec2[0], uniform->min.ivec2[0], uniform->max.ivec2[0], 0, 0);
+			addUniform(settings, &uniform->value.ivec2[1], uniform->min.ivec2[1], uniform->max.ivec2[1], 0, 1);
+			break;
+		case GL_INT_VEC3:
+			addUniform(settings, &uniform->value.ivec3[0], uniform->min.ivec3[0], uniform->max.ivec3[0], 0, 0);
+			addUniform(settings, &uniform->value.ivec3[1], uniform->min.ivec3[1], uniform->max.ivec3[1], 0, 1);
+			addUniform(settings, &uniform->value.ivec3[2], uniform->min.ivec3[2], uniform->max.ivec3[2], 0, 2);
+			break;
+		case GL_INT_VEC4:
+			addUniform(settings, &uniform->value.ivec4[0], uniform->min.ivec4[0], uniform->max.ivec4[0], 0, 0);
+			addUniform(settings, &uniform->value.ivec4[1], uniform->min.ivec4[1], uniform->max.ivec4[1], 0, 1);
+			addUniform(settings, &uniform->value.ivec4[2], uniform->min.ivec4[2], uniform->max.ivec4[2], 0, 2);
+			addUniform(settings, &uniform->value.ivec4[3], uniform->min.ivec4[3], uniform->max.ivec4[3], 0, 3);
+			break;
+		}
+		layout->addRow(shader->uniforms[u].readableName, settings);
+	}
+	return page;
+}
diff --git a/src/platform/qt/ShaderSelector.h b/src/platform/qt/ShaderSelector.h
index 73b45d73e..680891213 100644
--- a/src/platform/qt/ShaderSelector.h
+++ b/src/platform/qt/ShaderSelector.h
@@ -10,6 +10,7 @@
 
 #include "ui_ShaderSelector.h"
 
+struct GBAGLES2Shader;
 class QGridLayout;
 struct VideoShader;
 
@@ -36,6 +37,7 @@ private slots:
 private:
 	void addUniform(QGridLayout*, float* value, float min, float max, int y, int x);
 	void addUniform(QGridLayout*, int* value, int min, int max, int y, int x);
+	QWidget* makePage(GBAGLES2Shader*);
 
 	Ui::ShaderSelector m_ui;
 	Display* m_display;
diff --git a/src/platform/video-backend.h b/src/platform/video-backend.h
index 542b7aca2..aa930cbdf 100644
--- a/src/platform/video-backend.h
+++ b/src/platform/video-backend.h
@@ -36,6 +36,7 @@ struct VideoShader {
 	const char* name;
 	const char* author;
 	const char* description;
+	void* preprocessShader;
 	void* passes;
 	size_t nPasses;
 };