diff --git a/src/integrators/mlt/mlt_proc.cpp b/src/integrators/mlt/mlt_proc.cpp
index 7d820505..9cb5c320 100644
--- a/src/integrators/mlt/mlt_proc.cpp
+++ b/src/integrators/mlt/mlt_proc.cpp
@@ -189,7 +189,7 @@ public:
 							fail = true;
 					if (fail)
 						Log(EError, "Detected an unexpected path modification outside of the "
-							"specifed range after a mutation of type %s (k=%i)!",
+							"specified range after a mutation of type %s (k=%i)!",
 							muRec.toString().c_str(), current->length());
 				}
 				backup.release(*m_pool);
diff --git a/src/libbidir/manifold.cpp b/src/libbidir/manifold.cpp
index f6fd5aa4..e32a4c45 100644
--- a/src/libbidir/manifold.cpp
+++ b/src/libbidir/manifold.cpp
@@ -387,7 +387,8 @@ bool SpecularManifold::computeTangents() {
 
 	for (int i=0; i < n - 1; ++i) {
 		m_vertices[i].u = Li * m_vertices[i].c;
-		if (!(m_vertices[i+1].b - m_vertices[i+1].a * m_vertices[i].u).invert(Li))
+		Matrix2x2 temp = m_vertices[i+1].b - m_vertices[i+1].a * m_vertices[i].u;
+		if (!temp.invert(Li))
 			return false;
 	}
 
diff --git a/src/libbidir/mut_bidir.cpp b/src/libbidir/mut_bidir.cpp
index abdc6daf..a3befd3a 100644
--- a/src/libbidir/mut_bidir.cpp
+++ b/src/libbidir/mut_bidir.cpp
@@ -260,7 +260,7 @@ Float BidirectionalMutator::Q(const Path &source, const Path &proposal,
 
 		Float luminance = weight.getLuminance();
 
-		if (luminance <= 0) {
+		if (luminance <= 0 || !std::isfinite(luminance)) {
 			Log(EWarn, "Internal error: luminance = %f!", luminance);
 			continue;
 		}