diff --git a/src/MagnumPlugins/BasisImporter/Test/BasisImporterTest.cpp b/src/MagnumPlugins/BasisImporter/Test/BasisImporterTest.cpp
index 1c438b65b..9cef15513 100644
--- a/src/MagnumPlugins/BasisImporter/Test/BasisImporterTest.cpp
+++ b/src/MagnumPlugins/BasisImporter/Test/BasisImporterTest.cpp
@@ -36,7 +36,7 @@
 
 #include "configure.h"
 
-namespace Magnum { namespace Trade { namespace Test {
+namespace Magnum { namespace Trade { namespace Test { namespace {
 
 struct BasisImporterTest: TestSuite::Tester {
     explicit BasisImporterTest();
@@ -60,36 +60,43 @@ constexpr struct {
     const char* expectedFormatStr;
     const CompressedPixelFormat expectedFormat;
     const CompressedPixelFormat expectedFormatAlpha;
-    const bool needsPow2 = false;
+    const bool needsPow2;
 } FormatData[] {
     {
         "Etc1", "Etc1",
         CompressedPixelFormat::Etc2RGB8Unorm,
-        CompressedPixelFormat::Etc2RGBA8Unorm
+        CompressedPixelFormat::Etc2RGBA8Unorm,
+        false
     }, {
         "Etc2", "Etc2",
         CompressedPixelFormat::Etc2RGB8Unorm,
-        CompressedPixelFormat::Etc2RGBA8Unorm
+        CompressedPixelFormat::Etc2RGBA8Unorm,
+        false
     }, {
         "Bc1", "Bc1",
         CompressedPixelFormat::Bc1RGBUnorm,
-        CompressedPixelFormat::Bc1RGBAUnorm
+        CompressedPixelFormat::Bc1RGBAUnorm,
+        false
     }, {
         "Bc3", "Bc3",
         CompressedPixelFormat::Bc3RGBAUnorm,
-        CompressedPixelFormat::Bc3RGBAUnorm
+        CompressedPixelFormat::Bc3RGBAUnorm,
+        false
     }, {
         "Bc4", "Bc4",
         CompressedPixelFormat::Bc4RUnorm,
-        CompressedPixelFormat::Bc4RUnorm
+        CompressedPixelFormat::Bc4RUnorm,
+        false
     }, {
         "Bc5", "Bc5",
         CompressedPixelFormat::Bc5RGUnorm,
-        CompressedPixelFormat::Bc5RGUnorm
+        CompressedPixelFormat::Bc5RGUnorm,
+        false
     }, {
         "Bc7M6OpaqueOnly", "Bc7M6OpaqueOnly",
         CompressedPixelFormat::Bc7RGBAUnorm,
-        CompressedPixelFormat::Bc7RGBAUnorm
+        CompressedPixelFormat::Bc7RGBAUnorm,
+        false
     }, {
         "Pvrtc1_4OpaqueOnly", "Pvrtc1_4OpaqueOnly",
         CompressedPixelFormat::PvrtcRGB4bppUnorm,
@@ -101,6 +108,7 @@ constexpr struct {
 BasisImporterTest::BasisImporterTest() {
     addTests({&BasisImporterTest::empty,
               &BasisImporterTest::invalid,
+              &BasisImporterTest::unconfigured,
 
               &BasisImporterTest::openTwice,
               &BasisImporterTest::importTwice});
@@ -144,6 +152,7 @@ void BasisImporterTest::unconfigured() {
 
     CORRADE_VERIFY(importer->openFile(
         Utility::Directory::join(BASISIMPORTER_TEST_DIR, "rgb.basis")));
+    CORRADE_VERIFY(!importer->image2D(0));
 
     CORRADE_COMPARE(out.str(), "Trade::BasisImporter::image2D(): invalid configuration: format is expected to be one of: Etc1, Etc2, Bc1, Bc3, Bc4, Bc5, Bc7M6OpaqueOnly, Pvrtc1_4OpaqueOnly\n");
 }
@@ -232,6 +241,6 @@ void BasisImporterTest::rgba() {
     else CORRADE_COMPARE(image->size(), (Vector2i{27, 63}));
 }
 
-}}}
+}}}}
 
 CORRADE_TEST_MAIN(Magnum::Trade::Test::BasisImporterTest)