diff --git a/src/Magnum/Shaders/Test/DistanceFieldVectorTest.cpp b/src/Magnum/Shaders/Test/DistanceFieldVectorTest.cpp
index bdb22c184..5ec7a4c8f 100644
--- a/src/Magnum/Shaders/Test/DistanceFieldVectorTest.cpp
+++ b/src/Magnum/Shaders/Test/DistanceFieldVectorTest.cpp
@@ -105,7 +105,12 @@ void DistanceFieldVectorTest::drawUniformConstructNoInit() {
     a.materialId = 76;
 
     new(&a) DistanceFieldVectorDrawUniform{NoInit};
-    CORRADE_COMPARE(a.materialId, 76);
+    {
+        #if defined(__GNUC__) && __GNUC__*100 + __GNUC_MINOR__ >= 601 && __OPTIMIZE__
+        CORRADE_EXPECT_FAIL("GCC 6.1+ misoptimizes and overwrites the value.");
+        #endif
+        CORRADE_COMPARE(a.materialId, 76);
+    }
 
     CORRADE_VERIFY(std::is_nothrow_constructible<DistanceFieldVectorDrawUniform, NoInitT>::value);
 
@@ -168,8 +173,13 @@ void DistanceFieldVectorTest::materialUniformConstructNoInit() {
     a.outlineEnd = 0.37f;
 
     new(&a) DistanceFieldVectorMaterialUniform{NoInit};
-    CORRADE_COMPARE(a.color, 0x354565fc_rgbaf);
-    CORRADE_COMPARE(a.outlineEnd, 0.37f);
+    {
+        #if defined(__GNUC__) && __GNUC__*100 + __GNUC_MINOR__ >= 601 && __OPTIMIZE__
+        CORRADE_EXPECT_FAIL("GCC 6.1+ misoptimizes and overwrites the value.");
+        #endif
+        CORRADE_COMPARE(a.color, 0x354565fc_rgbaf);
+        CORRADE_COMPARE(a.outlineEnd, 0.37f);
+    }
 
     CORRADE_VERIFY(std::is_nothrow_constructible<DistanceFieldVectorMaterialUniform, NoInitT>::value);
 
diff --git a/src/Magnum/Shaders/Test/FlatTest.cpp b/src/Magnum/Shaders/Test/FlatTest.cpp
index 8365429ca..1a5a86df3 100644
--- a/src/Magnum/Shaders/Test/FlatTest.cpp
+++ b/src/Magnum/Shaders/Test/FlatTest.cpp
@@ -100,8 +100,13 @@ void FlatTest::drawUniformConstructNoInit() {
     a.alphaMask = 0.7f;
 
     new(&a) FlatDrawUniform{NoInit};
-    CORRADE_COMPARE(a.color, 0x354565fc_rgbaf);
-    CORRADE_COMPARE(a.alphaMask, 0.7f);
+    {
+        #if defined(__GNUC__) && __GNUC__*100 + __GNUC_MINOR__ >= 601 && __OPTIMIZE__
+        CORRADE_EXPECT_FAIL("GCC 6.1+ misoptimizes and overwrites the value.");
+        #endif
+        CORRADE_COMPARE(a.color, 0x354565fc_rgbaf);
+        CORRADE_COMPARE(a.alphaMask, 0.7f);
+    }
 
     CORRADE_VERIFY(std::is_nothrow_constructible<FlatDrawUniform, NoInitT>::value);
 
diff --git a/src/Magnum/Shaders/Test/GenericTest.cpp b/src/Magnum/Shaders/Test/GenericTest.cpp
index 744cfaae1..f6a03fcea 100644
--- a/src/Magnum/Shaders/Test/GenericTest.cpp
+++ b/src/Magnum/Shaders/Test/GenericTest.cpp
@@ -154,7 +154,12 @@ void GenericTest::projectionUniform2DConstructNoInit() {
     a.projectionMatrix[2] = {1.5f, 0.3f, 3.1f, 0.5f};
 
     new(&a) ProjectionUniform2D{NoInit};
-    CORRADE_COMPARE(a.projectionMatrix[2], (Vector4{1.5f, 0.3f, 3.1f, 0.5f}));
+    {
+        #if defined(__GNUC__) && __GNUC__*100 + __GNUC_MINOR__ >= 601 && __OPTIMIZE__
+        CORRADE_EXPECT_FAIL("GCC 6.1+ misoptimizes and overwrites the value.");
+        #endif
+        CORRADE_COMPARE(a.projectionMatrix[2], (Vector4{1.5f, 0.3f, 3.1f, 0.5f}));
+    }
 
     CORRADE_VERIFY(std::is_nothrow_constructible<ProjectionUniform2D, NoInitT>::value);
 
@@ -215,7 +220,12 @@ void GenericTest::projectionUniform3DConstructNoInit() {
     a.projectionMatrix[2] = {1.5f, 0.3f, 3.1f, 0.5f};
 
     new(&a) ProjectionUniform3D{NoInit};
-    CORRADE_COMPARE(a.projectionMatrix[2], (Vector4{1.5f, 0.3f, 3.1f, 0.5f}));
+    {
+        #if defined(__GNUC__) && __GNUC__*100 + __GNUC_MINOR__ >= 601 && __OPTIMIZE__
+        CORRADE_EXPECT_FAIL("GCC 6.1+ misoptimizes and overwrites the value.");
+        #endif
+        CORRADE_COMPARE(a.projectionMatrix[2], (Vector4{1.5f, 0.3f, 3.1f, 0.5f}));
+    }
 
     CORRADE_VERIFY(std::is_nothrow_constructible<ProjectionUniform3D, NoInitT>::value);
 
@@ -268,7 +278,12 @@ void GenericTest::transformationUniform2DConstructNoInit() {
     a.transformationMatrix[2] = {1.5f, 0.3f, 3.1f, 0.5f};
 
     new(&a) TransformationUniform2D{NoInit};
-    CORRADE_COMPARE(a.transformationMatrix[2], (Vector4{1.5f, 0.3f, 3.1f, 0.5f}));
+    {
+        #if defined(__GNUC__) && __GNUC__*100 + __GNUC_MINOR__ >= 601 && __OPTIMIZE__
+        CORRADE_EXPECT_FAIL("GCC 6.1+ misoptimizes and overwrites the value.");
+        #endif
+        CORRADE_COMPARE(a.transformationMatrix[2], (Vector4{1.5f, 0.3f, 3.1f, 0.5f}));
+    }
 
     CORRADE_VERIFY(std::is_nothrow_constructible<TransformationUniform2D, NoInitT>::value);
 
@@ -329,7 +344,12 @@ void GenericTest::transformationUniform3DConstructNoInit() {
     a.transformationMatrix[2] = {1.5f, 0.3f, 3.1f, 0.5f};
 
     new(&a) TransformationUniform3D{NoInit};
-    CORRADE_COMPARE(a.transformationMatrix[2], (Vector4{1.5f, 0.3f, 3.1f, 0.5f}));
+    {
+        #if defined(__GNUC__) && __GNUC__*100 + __GNUC_MINOR__ >= 601 && __OPTIMIZE__
+        CORRADE_EXPECT_FAIL("GCC 6.1+ misoptimizes and overwrites the value.");
+        #endif
+        CORRADE_COMPARE(a.transformationMatrix[2], (Vector4{1.5f, 0.3f, 3.1f, 0.5f}));
+    }
 
     CORRADE_VERIFY(std::is_nothrow_constructible<TransformationUniform3D, NoInitT>::value);
 
@@ -383,8 +403,13 @@ void GenericTest::textureTransformationUniformConstructNoInit() {
     a.offset = {2.7f, 0.3f};
 
     new(&a) TextureTransformationUniform{NoInit};
-    CORRADE_COMPARE(a.rotationScaling[1], (Vector2{2.5f, -3.0f}));
-    CORRADE_COMPARE(a.offset, (Vector2{2.7f, 0.3f}));
+    {
+        #if defined(__GNUC__) && __GNUC__*100 + __GNUC_MINOR__ >= 601 && __OPTIMIZE__
+        CORRADE_EXPECT_FAIL("GCC 6.1+ misoptimizes and overwrites the value.");
+        #endif
+        CORRADE_COMPARE(a.rotationScaling[1], (Vector2{2.5f, -3.0f}));
+        CORRADE_COMPARE(a.offset, (Vector2{2.7f, 0.3f}));
+    }
 
     CORRADE_VERIFY(std::is_nothrow_constructible<TextureTransformationUniform, NoInitT>::value);
 
diff --git a/src/Magnum/Shaders/Test/MeshVisualizerTest.cpp b/src/Magnum/Shaders/Test/MeshVisualizerTest.cpp
index e9bad7799..e6abe8c6a 100644
--- a/src/Magnum/Shaders/Test/MeshVisualizerTest.cpp
+++ b/src/Magnum/Shaders/Test/MeshVisualizerTest.cpp
@@ -120,7 +120,12 @@ void MeshVisualizerTest::drawUniform2DConstructNoInit() {
     a.materialId = 73;
 
     new(&a) MeshVisualizerDrawUniform2D{NoInit};
-    CORRADE_COMPARE(a.materialId, 73);
+    {
+        #if defined(__GNUC__) && __GNUC__*100 + __GNUC_MINOR__ >= 601 && __OPTIMIZE__
+        CORRADE_EXPECT_FAIL("GCC 6.1+ misoptimizes and overwrites the value.");
+        #endif
+        CORRADE_COMPARE(a.materialId, 73);
+    }
 
     CORRADE_VERIFY(std::is_nothrow_constructible<MeshVisualizerDrawUniform2D, NoInitT>::value);
 
@@ -187,8 +192,13 @@ void MeshVisualizerTest::drawUniform3DConstructNoInit() {
     a.materialId = 5;
 
     new(&a) MeshVisualizerDrawUniform3D{NoInit};
-    CORRADE_COMPARE(a.normalMatrix[2], (Vector4{1.5f, 0.3f, 3.1f, 0.5f}));
-    CORRADE_COMPARE(a.materialId, 5);
+    {
+        #if defined(__GNUC__) && __GNUC__*100 + __GNUC_MINOR__ >= 601 && __OPTIMIZE__
+        CORRADE_EXPECT_FAIL("GCC 6.1+ misoptimizes and overwrites the value.");
+        #endif
+        CORRADE_COMPARE(a.normalMatrix[2], (Vector4{1.5f, 0.3f, 3.1f, 0.5f}));
+        CORRADE_COMPARE(a.materialId, 5);
+    }
 
     CORRADE_VERIFY(std::is_nothrow_constructible<MeshVisualizerDrawUniform3D, NoInitT>::value);
 
@@ -269,8 +279,13 @@ void MeshVisualizerTest::materialUniformConstructNoInit() {
     a.lineWidth = 0.765f;
 
     new(&a) MeshVisualizerMaterialUniform{NoInit};
-    CORRADE_COMPARE(a.color, 0x354565fc_rgbaf);
-    CORRADE_COMPARE(a.lineWidth, 0.765f);
+    {
+        #if defined(__GNUC__) && __GNUC__*100 + __GNUC_MINOR__ >= 601 && __OPTIMIZE__
+        CORRADE_EXPECT_FAIL("GCC 6.1+ misoptimizes and overwrites the value.");
+        #endif
+        CORRADE_COMPARE(a.color, 0x354565fc_rgbaf);
+        CORRADE_COMPARE(a.lineWidth, 0.765f);
+    }
 
     CORRADE_VERIFY(std::is_nothrow_constructible<MeshVisualizerMaterialUniform, NoInitT>::value);
 
diff --git a/src/Magnum/Shaders/Test/PhongTest.cpp b/src/Magnum/Shaders/Test/PhongTest.cpp
index 7276b6440..e29330d3b 100644
--- a/src/Magnum/Shaders/Test/PhongTest.cpp
+++ b/src/Magnum/Shaders/Test/PhongTest.cpp
@@ -152,9 +152,14 @@ void PhongTest::drawUniformConstructNoInit() {
     a.lightCount = 7;
 
     new(&a) PhongDrawUniform{NoInit};
-    CORRADE_COMPARE(a.normalMatrix[2], (Vector4{1.5f, 0.3f, 3.1f, 0.5f}));
-    CORRADE_COMPARE(a.materialId, 5);
-    CORRADE_COMPARE(a.lightCount, 7);
+    {
+        #if defined(__GNUC__) && __GNUC__*100 + __GNUC_MINOR__ >= 601 && __OPTIMIZE__
+        CORRADE_EXPECT_FAIL("GCC 6.1+ misoptimizes and overwrites the value.");
+        #endif
+        CORRADE_COMPARE(a.normalMatrix[2], (Vector4{1.5f, 0.3f, 3.1f, 0.5f}));
+        CORRADE_COMPARE(a.materialId, 5);
+        CORRADE_COMPARE(a.lightCount, 7);
+    }
 
     CORRADE_VERIFY(std::is_nothrow_constructible<PhongDrawUniform, NoInitT>::value);
 
@@ -233,9 +238,14 @@ void PhongTest::materialUniformConstructNoInit() {
     a.alphaMask = 7.0f;
 
     new(&a) PhongMaterialUniform{NoInit};
-    CORRADE_COMPARE(a.diffuseColor, 0x354565fc_rgbaf);
-    CORRADE_COMPARE(a.normalTextureScale, 0.4f);
-    CORRADE_COMPARE(a.alphaMask, 7.0f);
+    {
+        #if defined(__GNUC__) && __GNUC__*100 + __GNUC_MINOR__ >= 601 && __OPTIMIZE__
+        CORRADE_EXPECT_FAIL("GCC 6.1+ misoptimizes and overwrites the value.");
+        #endif
+        CORRADE_COMPARE(a.diffuseColor, 0x354565fc_rgbaf);
+        CORRADE_COMPARE(a.normalTextureScale, 0.4f);
+        CORRADE_COMPARE(a.alphaMask, 7.0f);
+    }
 
     CORRADE_VERIFY(std::is_nothrow_constructible<PhongMaterialUniform, NoInitT>::value);
 
@@ -296,8 +306,13 @@ void PhongTest::lightUniformConstructNoInit() {
     a.range = 7.0f;
 
     new(&a) PhongLightUniform{NoInit};
-    CORRADE_COMPARE(a.color, 0x354565_rgbf);
-    CORRADE_COMPARE(a.range, 7.0f);
+    {
+        #if defined(__GNUC__) && __GNUC__*100 + __GNUC_MINOR__ >= 601 && __OPTIMIZE__
+        CORRADE_EXPECT_FAIL("GCC 6.1+ misoptimizes and overwrites the value.");
+        #endif
+        CORRADE_COMPARE(a.color, 0x354565_rgbf);
+        CORRADE_COMPARE(a.range, 7.0f);
+    }
 
     CORRADE_VERIFY(std::is_nothrow_constructible<PhongLightUniform, NoInitT>::value);
 
diff --git a/src/Magnum/Shaders/Test/VectorTest.cpp b/src/Magnum/Shaders/Test/VectorTest.cpp
index ce3be11bf..b3e49cd2b 100644
--- a/src/Magnum/Shaders/Test/VectorTest.cpp
+++ b/src/Magnum/Shaders/Test/VectorTest.cpp
@@ -96,8 +96,13 @@ void VectorTest::drawUniformConstructNoInit() {
     a.backgroundColor = 0x98769facb_rgbaf;
 
     new(&a) VectorDrawUniform{NoInit};
-    CORRADE_COMPARE(a.color, 0x354565fc_rgbaf);
-    CORRADE_COMPARE(a.backgroundColor, 0x98769facb_rgbaf);
+    {
+        #if defined(__GNUC__) && __GNUC__*100 + __GNUC_MINOR__ >= 601 && __OPTIMIZE__
+        CORRADE_EXPECT_FAIL("GCC 6.1+ misoptimizes and overwrites the value.");
+        #endif
+        CORRADE_COMPARE(a.color, 0x354565fc_rgbaf);
+        CORRADE_COMPARE(a.backgroundColor, 0x98769facb_rgbaf);
+    }
 
     CORRADE_VERIFY(std::is_nothrow_constructible<VectorDrawUniform, NoInitT>::value);