diff --git a/src/bsdfs/dipolebrdf.cpp b/src/bsdfs/dipolebrdf.cpp
index 9013c633..f8ace01a 100644
--- a/src/bsdfs/dipolebrdf.cpp
+++ b/src/bsdfs/dipolebrdf.cpp
@@ -53,6 +53,12 @@ public:
 		m_sigmaA = new ConstantSpectrumTexture(
 			props.getSpectrum("sigmaA", sigmaA));
 
+		if (props.hasProperty("sigmaT"))
+			m_sigmaT = new ConstantSpectrumTexture(
+				props.getSpectrum("sigmaT"));
+		if (props.hasProperty("albedo"))
+			m_albedo = new ConstantSpectrumTexture(
+				props.getSpectrum("albedo"));
 	}
 
 	DipoleBRDF(Stream *stream, InstanceManager *manager) 
@@ -103,9 +109,6 @@ public:
 		m_usesRayDifferentials = m_sigmaS->usesRayDifferentials()
 			|| m_sigmaA->usesRayDifferentials();
 
-		if ((m_sigmaS->getMaximum()+m_sigmaA->getMaximum()).isZero())
-			Log(EError, "Please specify nonzero sigmaS/sigmaA-values!");
-
 		/* relative index of refraction */
 		const Float eta = m_intIOR / m_extIOR;
 
diff --git a/src/bsdfs/hk.cpp b/src/bsdfs/hk.cpp
index b02c3517..bb6ba2b5 100644
--- a/src/bsdfs/hk.cpp
+++ b/src/bsdfs/hk.cpp
@@ -125,9 +125,16 @@ public:
 		/* Absorption coefficient of the layer */
 		m_sigmaA = new ConstantSpectrumTexture(
 			props.getSpectrum("sigmaA", sigmaA));
-
+		
 		/* Slab thickness in inverse units of sigmaS and sigmaA */
 		m_thickness = props.getFloat("thickness", 1); 
+		
+		if (props.hasProperty("sigmaT"))
+			m_sigmaT = new ConstantSpectrumTexture(
+				props.getSpectrum("sigmaT"));
+		if (props.hasProperty("albedo"))
+			m_albedo = new ConstantSpectrumTexture(
+				props.getSpectrum("albedo"));
 	}
 
 	HanrahanKrueger(Stream *stream, InstanceManager *manager) 
@@ -156,14 +163,14 @@ public:
 			m_albedo = NULL;
 		}
 
-		if ((m_sigmaS->getMaximum()+m_sigmaA->getMaximum()).isZero())
-			Log(EError, "Please specify nonzero sigmaS/sigmaA-values!");
-
 		int extraFlags = m_sigmaS->isConstant() && m_sigmaA->isConstant() ? 0 : ESpatiallyVarying;
 		m_components.clear();
 		m_components.push_back(EGlossyReflection   | EFrontSide | EBackSide | ECanUseSampler | extraFlags);
-		m_components.push_back(EGlossyTransmission | EFrontSide | EBackSide | ECanUseSampler | extraFlags);
-		m_components.push_back(EDeltaTransmission  | EFrontSide | EBackSide | ECanUseSampler | extraFlags);
+
+		if (m_thickness != std::numeric_limits<Float>::infinity()) {
+			m_components.push_back(EGlossyTransmission | EFrontSide | EBackSide | ECanUseSampler | extraFlags);
+			m_components.push_back(EDeltaTransmission  | EFrontSide | EBackSide | ECanUseSampler | extraFlags);
+		}
 
 		m_usesRayDifferentials = m_sigmaS->usesRayDifferentials()
 			|| m_sigmaA->usesRayDifferentials();
@@ -231,7 +238,8 @@ public:
 			/*                       Transmission component                         */
 			/* ==================================================================== */
 
-			if (hasGlossyTransmission && transmission) {
+			if (hasGlossyTransmission && transmission
+					&& m_thickness < std::numeric_limits<Float>::infinity()) {
 				MediumSamplingRecord dummy;
 				PhaseFunctionQueryRecord pRec(dummy,bRec.wi,bRec.wo);
 				const Float phaseVal = m_phase->eval(pRec);
diff --git a/src/bsdfs/sssbrdf.cpp b/src/bsdfs/sssbrdf.cpp
index a1e4b2a0..afe41f95 100644
--- a/src/bsdfs/sssbrdf.cpp
+++ b/src/bsdfs/sssbrdf.cpp
@@ -137,8 +137,11 @@ public:
 			m_coating->configure();
 
 			m_components.clear();
-			for (int i=0; i<m_coating->getComponentCount(); ++i)
-				m_components.push_back(m_coating->getType(i));
+			for (int i=0; i<m_coating->getComponentCount(); ++i) {
+				unsigned int type = m_coating->getType(i);
+				type &= ~BSDF::EBackSide;
+				m_components.push_back(type);
+			}
 			BSDF::configure();
 		}
 	}
@@ -148,18 +151,26 @@ public:
 	}
 
 	Spectrum eval(const BSDFQueryRecord &bRec, EMeasure measure) const {
+		if (Frame::cosTheta(bRec.wi) <= 0 || Frame::cosTheta(bRec.wo) <= 0)
+			return Spectrum(0.0f);
 		return m_coating->eval(bRec, measure);
 	}
 
 	Float pdf(const BSDFQueryRecord &bRec, EMeasure measure) const {
+		if (Frame::cosTheta(bRec.wi) <= 0 || Frame::cosTheta(bRec.wo) <= 0)
+			return 0.0f;
 		return m_coating->pdf(bRec, measure);
 	}
 
 	Spectrum sample(BSDFQueryRecord &bRec, Float &pdf, const Point2 &sample) const {
+		if (Frame::cosTheta(bRec.wi) <= 0)
+			return Spectrum(0.0f);
 		return m_coating->sample(bRec, pdf, sample);
 	}
 
 	Spectrum sample(BSDFQueryRecord &bRec, const Point2 &sample) const {
+		if (Frame::cosTheta(bRec.wi) <= 0)
+			return Spectrum(0.0f);
 		return m_coating->sample(bRec, sample);
 	}
 
diff --git a/src/textures/vertexcolors.cpp b/src/textures/vertexcolors.cpp
index 79fa0c68..b57f04a1 100644
--- a/src/textures/vertexcolors.cpp
+++ b/src/textures/vertexcolors.cpp
@@ -97,5 +97,5 @@ Shader *VertexColors::createShader(Renderer *renderer) const {
 	
 MTS_IMPLEMENT_CLASS(VertexColorShader, false, Shader)
 MTS_IMPLEMENT_CLASS_S(VertexColors, false, Texture)
-MTS_EXPORT_PLUGIN(VertexColors, "VertexColors texture");
+MTS_EXPORT_PLUGIN(VertexColors, "Vertex color texture");
 MTS_NAMESPACE_END