diff --git a/src/Math/Test/ComplexTest.cpp b/src/Math/Test/ComplexTest.cpp
index fb169465f..76136dbbf 100644
--- a/src/Math/Test/ComplexTest.cpp
+++ b/src/Math/Test/ComplexTest.cpp
@@ -255,6 +255,7 @@ void ComplexTest::angle() {
 
 void ComplexTest::rotation() {
     Complex a = Complex::rotation(Deg(120.0f));
+    CORRADE_COMPARE(a.length(), 1.0f);
     CORRADE_COMPARE(a, Complex(-0.5f, 0.8660254f));
     CORRADE_COMPARE_AS(a.rotationAngle(), Deg(120.0f), Rad);
 
diff --git a/src/Math/Test/DualQuaternionTest.cpp b/src/Math/Test/DualQuaternionTest.cpp
index ab0e52aad..7e64be636 100644
--- a/src/Math/Test/DualQuaternionTest.cpp
+++ b/src/Math/Test/DualQuaternionTest.cpp
@@ -190,6 +190,7 @@ void DualQuaternionTest::rotation() {
     CORRADE_COMPARE(o.str(), "Math::Quaternion::rotation(): axis must be normalized\n");
 
     DualQuaternion q = DualQuaternion::rotation(Deg(120.0f), axis);
+    CORRADE_COMPARE(q.length(), 1.0f);
     CORRADE_COMPARE(q, DualQuaternion({Vector3(0.5f, 0.5f, 0.5f), 0.5f}, {{}, 0.0f}));
     CORRADE_COMPARE_AS(q.rotationAngle(), Deg(120.0f), Deg);
     CORRADE_COMPARE(q.rotationAxis(), axis);
@@ -198,6 +199,7 @@ void DualQuaternionTest::rotation() {
 void DualQuaternionTest::translation() {
     Vector3 vec(1.0f, -3.5f, 0.5f);
     DualQuaternion q = DualQuaternion::translation(vec);
+    CORRADE_COMPARE(q.length(), 1.0f);
     CORRADE_COMPARE(q, DualQuaternion({}, {{0.5f, -1.75f, 0.25f}, 0.0f}));
     CORRADE_COMPARE(q.translation(), vec);
 }
diff --git a/src/Math/Test/QuaternionTest.cpp b/src/Math/Test/QuaternionTest.cpp
index b4472e768..11b28527b 100644
--- a/src/Math/Test/QuaternionTest.cpp
+++ b/src/Math/Test/QuaternionTest.cpp
@@ -235,6 +235,7 @@ void QuaternionTest::rotation() {
     CORRADE_COMPARE(o.str(), "Math::Quaternion::rotation(): axis must be normalized\n");
 
     Quaternion q = Quaternion::rotation(Deg(120.0f), axis);
+    CORRADE_COMPARE(q.length(), 1.0f);
     CORRADE_COMPARE(q, Quaternion(Vector3(0.5f, 0.5f, 0.5f), 0.5f));
     CORRADE_COMPARE_AS(q.rotationAngle(), Deg(120.0f), Deg);
     CORRADE_COMPARE(q.rotationAxis(), axis);