diff --git a/test/test_mixramp.cxx b/test/test_mixramp.cxx
index 83d266d48..7ed250717 100644
--- a/test/test_mixramp.cxx
+++ b/test/test_mixramp.cxx
@@ -44,6 +44,10 @@ public:
 		CPPUNIT_ASSERT(!std::isnan(mixramp_interpolate(foo, 3)));
 		free(foo);
 
+		foo = strdup(input);
+		CPPUNIT_ASSERT(std::isnan(mixramp_interpolate(foo, 6.1)));
+		free(foo);
+
 		foo = strdup(input);
 		CPPUNIT_ASSERT_DOUBLES_EQUAL(float(0.05),
 					     mixramp_interpolate(foo, 2),