diff --git a/src/Magnum/Audio/Test/ContextTest.cpp b/src/Magnum/Audio/Test/ContextTest.cpp
index 27cf5792c..9b8e044bb 100644
--- a/src/Magnum/Audio/Test/ContextTest.cpp
+++ b/src/Magnum/Audio/Test/ContextTest.cpp
@@ -73,23 +73,25 @@ void ContextTest::extensions() {
 
     std::set<std::string> unique;
 
-    /* Check that all extension indices are unique and are listed just once */
+    /* Check that all extension indices are unique, are listed just once etc. */
     for(const Extension& e: Extension::extensions()) {
+        CORRADE_ITERATION(e.string());
+
+        /** @todo convert to CORRADE_ERROR() when that's done */
+
         if(e.index() >= Implementation::ExtensionCount) {
-            Error{} << "Index" << e.index() << "used by" << e.string()
-                    << "larger than" << Implementation::ExtensionCount;
+            Error{} << "Index" << e.index() << "larger than" << Implementation::ExtensionCount;
             CORRADE_VERIFY(false);
         }
 
         if(used[e.index()]) {
-            Error{} << "Index" << e.index() << "used by both"
-                    << used[e.index()] << "and" << e.string();
+            Error{} << "Index" << e.index() << "already used by" << used[e.index()];
             CORRADE_VERIFY(false);
         }
 
         used[e.index()] = e.string();
         if(!unique.insert(e.string()).second) {
-            Error{} << "Extension" << e.string() << "listed more than once";
+            Error{} << "Extension listed more than once";
             CORRADE_VERIFY(false);
         }
     }
diff --git a/src/Magnum/GL/Test/ContextTest.cpp b/src/Magnum/GL/Test/ContextTest.cpp
index d9d2f8298..294550a63 100644
--- a/src/Magnum/GL/Test/ContextTest.cpp
+++ b/src/Magnum/GL/Test/ContextTest.cpp
@@ -126,21 +126,24 @@ void ContextTest::extensions() {
         Version::None})
     {
         for(const Extension& e: Extension::extensions(version)) {
+            CORRADE_ITERATION(version);
+            CORRADE_ITERATION(e.string());
+
+            /** @todo convert to CORRADE_ERROR() when that's done */
+
             if(e.index() >= GL::Implementation::ExtensionCount) {
-                Error{} << "Index" << e.index() << "used by" << e.string()
-                        << "larger than" << GL::Implementation::ExtensionCount;
+                Error{} << "Index" << e.index() << "larger than" << GL::Implementation::ExtensionCount;
                 CORRADE_VERIFY(false);
             }
 
             if(used[e.index()]) {
-                Error{} << "Index" << e.index() << "used by both"
-                        << used[e.index()] << "and" << e.string();
+                Error{} << "Index" << e.index() << "already used by" << used[e.index()];
                 CORRADE_VERIFY(false);
             }
 
             used[e.index()] = e.string();
             if(!unique.insert(e.string()).second) {
-                Error{} << "Extension" << e.string() << "listed more than once";
+                Error{} << "Extension listed more than once";
                 CORRADE_VERIFY(false);
             }
 
@@ -153,22 +156,20 @@ void ContextTest::extensions() {
                 && e.index() != Extensions::WEBGL::color_buffer_float::Index
                 #endif
             ) {
-                Error{} << "Extension" << e.string() << "should have core version"
-                    << version << "but has" << e.coreVersion();
+                Error{} << "Extension should have core version" << version << "but has" << e.coreVersion();
                 CORRADE_VERIFY(false);
             }
 
             #ifdef MAGNUM_TARGET_GLES2
             if(e.requiredVersion() != Version::GLES200) {
-                Error{} << "Extension" << e.string() << "should have required version"
-                    << Version::GLES200 << "but has" << e.requiredVersion();
+                Error{} << "Extension should have required version" << Version::GLES200 << "but has" << e.requiredVersion();
                 CORRADE_VERIFY(false);
             }
             #endif
 
             #if defined(MAGNUM_TARGET_GLES) && !defined(MAGNUM_TARGET_GLES2)
             if(e.coreVersion() == Version::GLES300 && e.index() != Extensions::MAGNUM::shader_vertex_id::Index) {
-                Error{} << "Extension" << e.string() << "has core version" << e.coreVersion() << "on a GLES3 build -- it shouldn't be present at all";
+                Error{} << "Extension has core version" << e.coreVersion() << "on a GLES3 build -- it shouldn't be present at all";
                 CORRADE_VERIFY(false);
             }
             #endif