diff --git a/prism/include/IntervalIteration.h b/prism/include/IntervalIteration.h
index eb13008c..7f02e9e2 100644
--- a/prism/include/IntervalIteration.h
+++ b/prism/include/IntervalIteration.h
@@ -37,7 +37,7 @@ private:
 	bool select_midpoint;
 
 public:
-	IntervalIteration(int flags) {
+	explicit IntervalIteration(int flags) {
 		ensure_monotonic_from_below = (flags & 0x01);
 		ensure_monotonic_from_above = (flags & 0x02);
 		select_midpoint = (flags & 0x04);
diff --git a/prism/include/Measures.h b/prism/include/Measures.h
index 8cc62f83..91d6487c 100644
--- a/prism/include/Measures.h
+++ b/prism/include/Measures.h
@@ -45,7 +45,7 @@ private:
 
 public:
 	/** Constructor, set relative flag */
-	MeasureSupNorm(bool relative) : relative(relative) {
+	explicit MeasureSupNorm(bool relative) : relative(relative) {
 		reset();
 	}
 
@@ -117,7 +117,7 @@ private:
 
 public:
 	/** Constructor, set relative flag */
-	MeasureSupNormInterval(bool relative) : relative(relative) {
+	explicit MeasureSupNormInterval(bool relative) : relative(relative) {
 		reset();
 	}