diff --git a/intern/cycles/kernel/closure/volume.h b/intern/cycles/kernel/closure/volume.h
index f30b30c8c76..f4932568c1f 100644
--- a/intern/cycles/kernel/closure/volume.h
+++ b/intern/cycles/kernel/closure/volume.h
@@ -53,11 +53,6 @@ ccl_device float3 volume_transparent_eval_phase(const ShaderClosure *sc, const f
 
 ccl_device float3 volume_eval_phase(KernelGlobals *kg, const ShaderClosure *sc, const float3 omega_in, const float3 omega_out)
 {
-#ifdef __OSL__
-	if(kg->osl && sc->prim)
-		return OSLShader::volume_eval_phase(sc, omega_in, omega_out);
-#endif
-
 	float3 eval;
 
 	switch(sc->type) {
diff --git a/intern/cycles/kernel/kernel_shader.h b/intern/cycles/kernel/kernel_shader.h
index 77154ce3aef..dbc705ea791 100644
--- a/intern/cycles/kernel/kernel_shader.h
+++ b/intern/cycles/kernel/kernel_shader.h
@@ -764,11 +764,6 @@ ccl_device float3 shader_bssrdf_sum(ShaderData *sd, float3 *N_, float *texture_b
 
 ccl_device float3 emissive_eval(KernelGlobals *kg, ShaderData *sd, ShaderClosure *sc)
 {
-#ifdef __OSL__
-	if(kg->osl && sc->prim)
-		return OSLShader::emissive_eval(sd, sc);
-#endif
-
 	return emissive_simple_eval(sd->Ng, sd->I);
 }
 
diff --git a/intern/cycles/kernel/osl/background.cpp b/intern/cycles/kernel/osl/background.cpp
index eed4446cddc..2facced0914 100644
--- a/intern/cycles/kernel/osl/background.cpp
+++ b/intern/cycles/kernel/osl/background.cpp
@@ -46,14 +46,9 @@ using namespace OSL;
 /// to return a color in background shaders. No methods,
 /// only the weight is taking into account
 ///
-class GenericBackgroundClosure : public OSL::BackgroundClosure {
+class GenericBackgroundClosure : public CClosurePrimitive {
 public:
-	GenericBackgroundClosure() {}
-
-	void setup() {};
-	size_t memsize() const { return sizeof(*this); }
-	const char *name() const { return "background"; }
-	void print_on(std::ostream &out) const { out << name() << " ()"; }
+	GenericBackgroundClosure() : CClosurePrimitive(Background) {}
 };
 
 /// Holdout closure
@@ -63,14 +58,9 @@ public:
 /// point. No parameters, only the weight will be
 /// used
 ///
-class HoldoutClosure : ClosurePrimitive {
+class HoldoutClosure : CClosurePrimitive {
 public:
-	HoldoutClosure () : ClosurePrimitive(Holdout) {}
-
-	void setup() {};
-	size_t memsize() const { return sizeof(*this); }
-	const char *name() const { return "holdout"; }
-	void print_on(std::ostream &out) const { out << name() << " ()"; }
+	HoldoutClosure () : CClosurePrimitive(Holdout) {}
 };
 
 /// ambient occlusion closure
@@ -79,14 +69,9 @@ public:
 /// to return a color in ambient occlusion shaders. No methods,
 /// only the weight is taking into account
 ///
-class AmbientOcclusionClosure : public ClosurePrimitive {
+class AmbientOcclusionClosure : public CClosurePrimitive {
 public:
-	AmbientOcclusionClosure () : ClosurePrimitive((ClosurePrimitive::Category)AmbientOcclusion) {}
-
-	void setup() {};
-	size_t memsize() const { return sizeof(*this); }
-	const char *name() const { return "ambient_occlusion"; }
-	void print_on(std::ostream &out) const { out << name() << " ()"; }
+	AmbientOcclusionClosure () : CClosurePrimitive(AmbientOcclusion) {}
 };
 
 ClosureParam *closure_background_params()
@@ -98,7 +83,7 @@ ClosureParam *closure_background_params()
 	return params;
 }
 
-CLOSURE_PREPARE(closure_background_prepare, GenericBackgroundClosure)
+CCLOSURE_PREPARE(closure_background_prepare, GenericBackgroundClosure)
 
 ClosureParam *closure_holdout_params()
 {
@@ -108,7 +93,7 @@ ClosureParam *closure_holdout_params()
 	return params;
 }
 
-CLOSURE_PREPARE(closure_holdout_prepare, HoldoutClosure)
+CCLOSURE_PREPARE(closure_holdout_prepare, HoldoutClosure)
 
 ClosureParam *closure_ambient_occlusion_params()
 {
@@ -119,7 +104,7 @@ ClosureParam *closure_ambient_occlusion_params()
 	return params;
 }
 
-CLOSURE_PREPARE(closure_ambient_occlusion_prepare, AmbientOcclusionClosure)
+CCLOSURE_PREPARE(closure_ambient_occlusion_prepare, AmbientOcclusionClosure)
 
 CCL_NAMESPACE_END
 
diff --git a/intern/cycles/kernel/osl/bsdf_diffuse_ramp.cpp b/intern/cycles/kernel/osl/bsdf_diffuse_ramp.cpp
index a320bea118a..0e8193aa68c 100644
--- a/intern/cycles/kernel/osl/bsdf_diffuse_ramp.cpp
+++ b/intern/cycles/kernel/osl/bsdf_diffuse_ramp.cpp
@@ -46,14 +46,10 @@ using namespace OSL;
 
 class DiffuseRampClosure : public CBSDFClosure {
 public:
-	DiffuseRampClosure() : CBSDFClosure(LABEL_DIFFUSE) {}
 	Color3 colors[8];
 	float3 fcolors[8];
 
-	size_t memsize() const { return sizeof(*this); }
-	const char *name() const { return "diffuse_ramp"; }
-
-	void setup()
+	DiffuseRampClosure() : CBSDFClosure(LABEL_DIFFUSE)
 	{
 		sc.prim = this;
 		m_shaderdata_flag = bsdf_diffuse_ramp_setup(&sc);
@@ -62,21 +58,11 @@ public:
 			fcolors[i] = TO_FLOAT3(colors[i]);
 	}
 
-	bool mergeable(const ClosurePrimitive *other) const
-	{
-		return false;
-	}
-
 	void blur(float roughness)
 	{
 		bsdf_diffuse_ramp_blur(&sc, roughness);
 	}
 
-	void print_on(std::ostream &out) const
-	{
-		out << name() << " ((" << sc.N[0] << ", " << sc.N[1] << ", " << sc.N[2] << "))";
-	}
-
 	float3 eval_reflect(const float3 &omega_out, const float3 &omega_in, float& pdf) const
 	{
 		return bsdf_diffuse_ramp_eval_reflect(&sc, fcolors, omega_out, omega_in, &pdf);
@@ -109,7 +95,7 @@ ClosureParam *closure_bsdf_diffuse_ramp_params()
 	return params;
 }
 
-CLOSURE_PREPARE(closure_bsdf_diffuse_ramp_prepare, DiffuseRampClosure)
+CCLOSURE_PREPARE(closure_bsdf_diffuse_ramp_prepare, DiffuseRampClosure)
 
 CCL_NAMESPACE_END
 
diff --git a/intern/cycles/kernel/osl/bsdf_phong_ramp.cpp b/intern/cycles/kernel/osl/bsdf_phong_ramp.cpp
index ef656ee7d5f..3c95bfc119e 100644
--- a/intern/cycles/kernel/osl/bsdf_phong_ramp.cpp
+++ b/intern/cycles/kernel/osl/bsdf_phong_ramp.cpp
@@ -45,14 +45,10 @@ using namespace OSL;
 
 class PhongRampClosure : public CBSDFClosure {
 public:
-	PhongRampClosure() : CBSDFClosure(LABEL_GLOSSY) {}
 	Color3 colors[8];
 	float3 fcolors[8];
 
-	size_t memsize() const { return sizeof(*this); }
-	const char *name() const { return "phong_ramp"; }
-
-	void setup()
+	PhongRampClosure() : CBSDFClosure(LABEL_GLOSSY)
 	{
 		sc.prim = this;
 		m_shaderdata_flag = bsdf_phong_ramp_setup(&sc);
@@ -61,21 +57,11 @@ public:
 			fcolors[i] = TO_FLOAT3(colors[i]);
 	}
 
-	bool mergeable(const ClosurePrimitive *other) const
-	{
-		return false;
-	}
-
 	void blur(float roughness)
 	{
 		bsdf_phong_ramp_blur(&sc, roughness);
 	}
 
-	void print_on(std::ostream &out) const
-	{
-		out << name() << " ((" << sc.N[0] << ", " << sc.N[1] << ", " << sc.N[2] << "))";
-	}
-
 	float3 eval_reflect(const float3 &omega_out, const float3 &omega_in, float& pdf) const
 	{
 		return bsdf_phong_ramp_eval_reflect(&sc, fcolors, omega_out, omega_in, &pdf);
@@ -109,7 +95,7 @@ ClosureParam *closure_bsdf_phong_ramp_params()
 	return params;
 }
 
-CLOSURE_PREPARE(closure_bsdf_phong_ramp_prepare, PhongRampClosure)
+CCLOSURE_PREPARE(closure_bsdf_phong_ramp_prepare, PhongRampClosure)
 
 CCL_NAMESPACE_END
 
diff --git a/intern/cycles/kernel/osl/emissive.cpp b/intern/cycles/kernel/osl/emissive.cpp
index 7d9fa81dbdd..02935542c56 100644
--- a/intern/cycles/kernel/osl/emissive.cpp
+++ b/intern/cycles/kernel/osl/emissive.cpp
@@ -50,18 +50,9 @@ using namespace OSL;
 /// outer_angle limit. It can also behave as a lambertian emitter
 /// if the provided angles are PI/2, which is the default
 ///
-class GenericEmissiveClosure : public EmissiveClosure {
+class GenericEmissiveClosure : public CClosurePrimitive {
 public:
-	GenericEmissiveClosure() { }
-
-	void setup() {}
-	size_t memsize() const { return sizeof(*this); }
-	const char *name() const { return "emission"; }
-
-	void print_on(std::ostream &out) const
-	{
-		out << name() << "()";
-	}
+	GenericEmissiveClosure() : CClosurePrimitive(Emissive) { }
 
 	Color3 eval(const Vec3 &Ng, const Vec3 &omega_out) const
 	{
@@ -92,7 +83,7 @@ ClosureParam *closure_emission_params()
 	return params;
 }
 
-CLOSURE_PREPARE(closure_emission_prepare, GenericEmissiveClosure)
+CCLOSURE_PREPARE(closure_emission_prepare, GenericEmissiveClosure)
 
 CCL_NAMESPACE_END
 
diff --git a/intern/cycles/kernel/osl/osl_bssrdf.cpp b/intern/cycles/kernel/osl/osl_bssrdf.cpp
index 975967c0bbb..887015c886e 100644
--- a/intern/cycles/kernel/osl/osl_bssrdf.cpp
+++ b/intern/cycles/kernel/osl/osl_bssrdf.cpp
@@ -51,24 +51,11 @@ using namespace OSL;
 
 class CubicBSSRDFClosure : public CBSSRDFClosure {
 public:
-	size_t memsize() const { return sizeof(*this); }
-	const char *name() const { return "bssrdf_cubic"; }
-
-	void setup()
+	CubicBSSRDFClosure()
 	{
 		sc.type = CLOSURE_BSSRDF_CUBIC_ID;
 		sc.data0 = fabsf(average(radius));
 	}
-
-	bool mergeable(const ClosurePrimitive *other) const
-	{
-		return false;
-	}
-
-	void print_on(std::ostream &out) const
-	{
-		out << name() << " ((" << sc.N[0] << ", " << sc.N[1] << ", " << sc.N[2] << "))";
-	}
 };
 
 ClosureParam *closure_bssrdf_cubic_params()
@@ -96,30 +83,17 @@ ClosureParam *closure_bssrdf_cubic_extended_params()
 	return params;
 }
 
-CLOSURE_PREPARE(closure_bssrdf_cubic_prepare, CubicBSSRDFClosure)
+CCLOSURE_PREPARE(closure_bssrdf_cubic_prepare, CubicBSSRDFClosure)
 
 /* Gaussian */
 
 class GaussianBSSRDFClosure : public CBSSRDFClosure {
 public:
-	size_t memsize() const { return sizeof(*this); }
-	const char *name() const { return "bssrdf_gaussian"; }
-
-	void setup()
+	GaussianBSSRDFClosure()
 	{
 		sc.type = CLOSURE_BSSRDF_GAUSSIAN_ID;
 		sc.data0 = fabsf(average(radius));
 	}
-
-	bool mergeable(const ClosurePrimitive *other) const
-	{
-		return false;
-	}
-
-	void print_on(std::ostream &out) const
-	{
-		out << name() << " ((" << sc.N[0] << ", " << sc.N[1] << ", " << sc.N[2] << "))";
-	}
 };
 
 ClosureParam *closure_bssrdf_gaussian_params()
@@ -146,7 +120,7 @@ ClosureParam *closure_bssrdf_gaussian_extended_params()
 	return params;
 }
 
-CLOSURE_PREPARE(closure_bssrdf_gaussian_prepare, GaussianBSSRDFClosure)
+CCLOSURE_PREPARE(closure_bssrdf_gaussian_prepare, GaussianBSSRDFClosure)
 
 CCL_NAMESPACE_END
 
diff --git a/intern/cycles/kernel/osl/osl_bssrdf.h b/intern/cycles/kernel/osl/osl_bssrdf.h
index fc1a4c587cc..6aee2c28ea8 100644
--- a/intern/cycles/kernel/osl/osl_bssrdf.h
+++ b/intern/cycles/kernel/osl/osl_bssrdf.h
@@ -37,20 +37,20 @@
 #include <OSL/oslexec.h>
 #include <OSL/genclosure.h>
 
+#include "osl_closures.h"
+
 #include "kernel_types.h"
 
 #include "util_types.h"
 
 CCL_NAMESPACE_BEGIN
 
-class CBSSRDFClosure : public OSL::ClosurePrimitive {
+class CBSSRDFClosure : public CClosurePrimitive {
 public:
 	ShaderClosure sc;
 	float3 radius;
 
-	CBSSRDFClosure() : OSL::ClosurePrimitive(BSSRDF) { memset(&sc, 0, sizeof(sc)); }
-	~CBSSRDFClosure() { }
-
+	CBSSRDFClosure() : CClosurePrimitive(BSSRDF) { }
 	int scattering() const { return LABEL_DIFFUSE; }
 };
 
diff --git a/intern/cycles/kernel/osl/osl_closures.cpp b/intern/cycles/kernel/osl/osl_closures.cpp
index 221406a1716..340e4492584 100644
--- a/intern/cycles/kernel/osl/osl_closures.cpp
+++ b/intern/cycles/kernel/osl/osl_closures.cpp
@@ -171,25 +171,16 @@ BSDF_CLOSURE_CLASS_END(HairTransmission, hair_transmission)
 
 /* Registration */
 
-static void generic_closure_setup(OSL::RendererServices *, int id, void *data)
-{
-	assert(data);
-	OSL::ClosurePrimitive *prim = (OSL::ClosurePrimitive *)data;
-	prim->setup();
-}
-
-static bool generic_closure_compare(int id, const void *dataA, const void *dataB)
-{
-	assert(dataA && dataB);
-
-	OSL::ClosurePrimitive *primA = (OSL::ClosurePrimitive *)dataA;
-	OSL::ClosurePrimitive *primB = (OSL::ClosurePrimitive *)dataB;
-	return primA->mergeable(primB);
-}
-
 static void register_closure(OSL::ShadingSystem *ss, const char *name, int id, OSL::ClosureParam *params, OSL::PrepareClosureFunc prepare)
 {
-	ss->register_closure(name, id, params, prepare, generic_closure_setup, generic_closure_compare);
+	/* optimization: it's possible to not use a prepare function at all and
+	 * only initialize the actual class when accessing the closure component
+	 * data, but then we need to map the id to the class somehow */
+#ifdef CLOSURE_PREPARE
+	ss->register_closure(name, id, params, prepare, NULL, NULL);
+#else
+	ss->register_closure(name, id, params, prepare, NULL);
+#endif
 }
 
 void OSLShader::register_closures(OSLShadingSystem *ss_)
diff --git a/intern/cycles/kernel/osl/osl_closures.h b/intern/cycles/kernel/osl/osl_closures.h
index 6632c2c57e5..46d645d69b1 100644
--- a/intern/cycles/kernel/osl/osl_closures.h
+++ b/intern/cycles/kernel/osl/osl_closures.h
@@ -66,36 +66,51 @@ void closure_westin_sheen_prepare(OSL::RendererServices *, int id, void *data);
 void closure_bssrdf_cubic_prepare(OSL::RendererServices *, int id, void *data);
 void closure_bssrdf_gaussian_prepare(OSL::RendererServices *, int id, void *data);
 
-enum {
-	AmbientOcclusion = 100
-};
-
-#define CLOSURE_PREPARE(name, classname)          \
+#define CCLOSURE_PREPARE(name, classname)          \
 void name(RendererServices *, int id, void *data) \
 {                                                 \
 	memset(data, 0, sizeof(classname));           \
 	new (data) classname();                       \
 }
 
-#define CLOSURE_PREPARE_STATIC(name, classname) static CLOSURE_PREPARE(name, classname)
+#define CCLOSURE_PREPARE_STATIC(name, classname) static CCLOSURE_PREPARE(name, classname)
 
 #define CLOSURE_FLOAT3_PARAM(st, fld) \
-    { TypeDesc::TypeVector, reckless_offsetof(st, fld), NULL, sizeof(OSL::Vec3) }
+	{ TypeDesc::TypeVector, reckless_offsetof(st, fld), NULL, sizeof(OSL::Vec3) }
 
 #define TO_VEC3(v) OSL::Vec3(v.x, v.y, v.z)
 #define TO_COLOR3(v) OSL::Color3(v.x, v.y, v.z)
 #define TO_FLOAT3(v) make_float3(v[0], v[1], v[2])
 
+/* Closure */
+
+class CClosurePrimitive {
+public:
+	enum Category {
+		BSDF,             ///< Reflective and/or transmissive surface
+		BSSRDF,           ///< Sub-surface light transfer
+		Emissive,         ///< Light emission
+		Background,       ///< Background emission
+		Volume,           ///< Volume scattering
+		Holdout,          ///< Holdout from alpha
+		AmbientOcclusion, ///< Ambient occlusion
+	};
+
+	CClosurePrimitive (Category category_) : category (category_) { }
+	virtual ~CClosurePrimitive() {}
+
+	Category category;
+};
+
 /* BSDF */
 
-class CBSDFClosure : public OSL::ClosurePrimitive {
+class CBSDFClosure : public CClosurePrimitive {
 public:
 	ShaderClosure sc;
 
-	CBSDFClosure(int scattering) : OSL::ClosurePrimitive(BSDF),
+	CBSDFClosure(int scattering) : CClosurePrimitive(BSDF),
 	  m_scattering_label(scattering), m_shaderdata_flag(0)
-	{ memset(&sc, 0, sizeof(sc)); }
-	~CBSDFClosure() { }
+	{ }
 
 	int scattering() const { return m_scattering_label; }
 	int shaderdata_flag() const { return m_shaderdata_flag; }
@@ -119,30 +134,16 @@ protected:
 \
 class Upper##Closure : public CBSDFClosure { \
 public: \
-	Upper##Closure() : CBSDFClosure(TYPE) {} \
-	size_t memsize() const { return sizeof(*this); } \
-	const char *name() const { return #lower; } \
-\
-	void setup() \
+	Upper##Closure() : CBSDFClosure(TYPE) \
 	{ \
 		sc.prim = NULL; \
 		m_shaderdata_flag = bsdf_##lower##_setup(&sc); \
 	} \
 \
-	bool mergeable(const ClosurePrimitive *other) const \
-	{ \
-		return false; \
-	} \
-	\
 	void blur(float roughness) \
 	{ \
 		bsdf_##svmlower##_blur(&sc, roughness); \
 	} \
-\
-	void print_on(std::ostream &out) const \
-	{ \
-		out << name() << " ((" << sc.N[0] << ", " << sc.N[1] << ", " << sc.N[2] << "))"; \
-	} \
 \
 	float3 eval_reflect(const float3 &omega_out, const float3 &omega_in, float& pdf) const \
 	{ \
@@ -178,7 +179,7 @@ static ClosureParam *bsdf_##lower##_params() \
 	return params; \
 } \
 \
-CLOSURE_PREPARE_STATIC(bsdf_##lower##_prepare, Upper##Closure)
+CCLOSURE_PREPARE_STATIC(bsdf_##lower##_prepare, Upper##Closure)
 
 CCL_NAMESPACE_END
 
diff --git a/intern/cycles/kernel/osl/osl_shader.cpp b/intern/cycles/kernel/osl/osl_shader.cpp
index 18e8fee4348..146736ba799 100644
--- a/intern/cycles/kernel/osl/osl_shader.cpp
+++ b/intern/cycles/kernel/osl/osl_shader.cpp
@@ -146,7 +146,7 @@ static void flatten_surface_closure_tree(ShaderData *sd, int path_flag,
 
 	if (closure->type == OSL::ClosureColor::COMPONENT) {
 		OSL::ClosureComponent *comp = (OSL::ClosureComponent *)closure;
-		OSL::ClosurePrimitive *prim = (OSL::ClosurePrimitive *)comp->data();
+		CClosurePrimitive *prim = (CClosurePrimitive *)comp->data();
 
 		if (prim) {
 			ShaderClosure sc;
@@ -156,8 +156,8 @@ static void flatten_surface_closure_tree(ShaderData *sd, int path_flag,
 			sc.weight = weight;
 #endif
 
-			switch (prim->category()) {
-				case OSL::ClosurePrimitive::BSDF: {
+			switch (prim->category) {
+				case CClosurePrimitive::BSDF: {
 					CBSDFClosure *bsdf = (CBSDFClosure *)prim;
 					int scattering = bsdf->scattering();
 
@@ -191,7 +191,7 @@ static void flatten_surface_closure_tree(ShaderData *sd, int path_flag,
 					}
 					break;
 				}
-				case OSL::ClosurePrimitive::Emissive: {
+				case CClosurePrimitive::Emissive: {
 					/* sample weight */
 					float sample_weight = fabsf(average(weight));
 
@@ -208,7 +208,7 @@ static void flatten_surface_closure_tree(ShaderData *sd, int path_flag,
 					}
 					break;
 				}
-				case AmbientOcclusion: {
+				case CClosurePrimitive::AmbientOcclusion: {
 					/* sample weight */
 					float sample_weight = fabsf(average(weight));
 
@@ -224,7 +224,7 @@ static void flatten_surface_closure_tree(ShaderData *sd, int path_flag,
 					}
 					break;
 				}
-				case OSL::ClosurePrimitive::Holdout: {
+				case CClosurePrimitive::Holdout: {
 					sc.sample_weight = 0.0f;
 					sc.type = CLOSURE_HOLDOUT_ID;
 					sc.data0 = 0.0f;
@@ -237,7 +237,7 @@ static void flatten_surface_closure_tree(ShaderData *sd, int path_flag,
 					}
 					break;
 				}
-				case OSL::ClosurePrimitive::BSSRDF: {
+				case CClosurePrimitive::BSSRDF: {
 					CBSSRDFClosure *bssrdf = (CBSSRDFClosure *)prim;
 					float sample_weight = fabsf(average(weight));
 
@@ -280,10 +280,8 @@ static void flatten_surface_closure_tree(ShaderData *sd, int path_flag,
 					}
 					break;
 				}
-				case OSL::ClosurePrimitive::Debug:
-					break; /* not implemented */
-				case OSL::ClosurePrimitive::Background:
-				case OSL::ClosurePrimitive::Volume:
+				case CClosurePrimitive::Background:
+				case CClosurePrimitive::Volume:
 					break; /* not relevant */
 			}
 		}
@@ -332,9 +330,9 @@ static float3 flatten_background_closure_tree(const OSL::ClosureColor *closure)
 
 	if (closure->type == OSL::ClosureColor::COMPONENT) {
 		OSL::ClosureComponent *comp = (OSL::ClosureComponent *)closure;
-		OSL::ClosurePrimitive *prim = (OSL::ClosurePrimitive *)comp->data();
+		CClosurePrimitive *prim = (CClosurePrimitive *)comp->data();
 
-		if (prim && prim->category() == OSL::ClosurePrimitive::Background)
+		if (prim && prim->category == CClosurePrimitive::Background)
 #ifdef OSL_SUPPORTS_WEIGHTED_CLOSURE_COMPONENTS
 			return TO_FLOAT3(comp->w);
 #else
@@ -387,7 +385,7 @@ static void flatten_volume_closure_tree(ShaderData *sd,
 
 	if (closure->type == OSL::ClosureColor::COMPONENT) {
 		OSL::ClosureComponent *comp = (OSL::ClosureComponent *)closure;
-		OSL::ClosurePrimitive *prim = (OSL::ClosurePrimitive *)comp->data();
+		CClosurePrimitive *prim = (CClosurePrimitive *)comp->data();
 
 		if (prim) {
 			ShaderClosure sc;
@@ -397,8 +395,8 @@ static void flatten_volume_closure_tree(ShaderData *sd,
 			sc.weight = weight;
 #endif
 
-			switch (prim->category()) {
-				case OSL::ClosurePrimitive::Volume: {
+			switch (prim->category) {
+				case CClosurePrimitive::Volume: {
 					/* sample weight */
 					float sample_weight = fabsf(average(weight));
 
@@ -413,13 +411,13 @@ static void flatten_volume_closure_tree(ShaderData *sd,
 						sd->closure[sd->num_closure++] = sc;
 					break;
 				}
-				case OSL::ClosurePrimitive::Holdout:
-				case OSL::ClosurePrimitive::Debug:
+				case CClosurePrimitive::Holdout:
 					break; /* not implemented */
-				case OSL::ClosurePrimitive::Background:
-				case OSL::ClosurePrimitive::BSDF:
-				case OSL::ClosurePrimitive::Emissive:
-				case OSL::ClosurePrimitive::BSSRDF:
+				case CClosurePrimitive::Background:
+				case CClosurePrimitive::BSDF:
+				case CClosurePrimitive::Emissive:
+				case CClosurePrimitive::BSSRDF:
+				case CClosurePrimitive::AmbientOcclusion:
 					break; /* not relevant */
 			}
 		}
@@ -509,25 +507,6 @@ void OSLShader::bsdf_blur(ShaderClosure *sc, float roughness)
 	bsdf->blur(roughness);
 }
 
-/* Emissive Closure */
-
-float3 OSLShader::emissive_eval(const ShaderData *sd, const ShaderClosure *sc)
-{
-	OSL::EmissiveClosure *emissive = (OSL::EmissiveClosure *)sc->prim;
-	OSL::Color3 emissive_eval = emissive->eval(TO_VEC3(sd->Ng), TO_VEC3(sd->I));
-
-	return TO_FLOAT3(emissive_eval);
-}
-
-/* Volume Closure */
-
-float3 OSLShader::volume_eval_phase(const ShaderClosure *sc, const float3 omega_in, const float3 omega_out)
-{
-	OSL::VolumeClosure *volume = (OSL::VolumeClosure *)sc->prim;
-	OSL::Color3 volume_eval = volume->eval_phase(TO_VEC3(omega_in), TO_VEC3(omega_out));
-	return TO_FLOAT3(volume_eval) * sc->weight;
-}
-
 /* Attributes */
 
 int OSLShader::find_attribute(KernelGlobals *kg, const ShaderData *sd, uint id, AttributeElement *elem)
diff --git a/intern/cycles/kernel/osl/osl_shader.h b/intern/cycles/kernel/osl/osl_shader.h
index 777ecb6af81..2520b703ab7 100644
--- a/intern/cycles/kernel/osl/osl_shader.h
+++ b/intern/cycles/kernel/osl/osl_shader.h
@@ -66,11 +66,6 @@ public:
 	                        const float3& omega_in, float& pdf);
 	static void bsdf_blur(ShaderClosure *sc, float roughness);
 
-	static float3 emissive_eval(const ShaderData *sd, const ShaderClosure *sc);
-
-	static float3 volume_eval_phase(const ShaderClosure *sc,
-	                                const float3 omega_in, const float3 omega_out);
-
 	/* attributes */
 	static int find_attribute(KernelGlobals *kg, const ShaderData *sd, uint id, AttributeElement *elem);
 };