diff --git a/src/Magnum/MeshTools/Concatenate.cpp b/src/Magnum/MeshTools/Concatenate.cpp
index f50596b5e..ff56ddb57 100644
--- a/src/Magnum/MeshTools/Concatenate.cpp
+++ b/src/Magnum/MeshTools/Concatenate.cpp
@@ -189,6 +189,14 @@ Trade::MeshData concatenate(const Containers::ArrayView<const Containers::Refere
     CORRADE_ASSERT(!meshes.empty(),
         "MeshTools::concatenate(): expected at least one mesh",
         (Trade::MeshData{MeshPrimitive::Points, 0}));
+    #ifndef CORRADE_NO_ASSERT
+    for(std::size_t i = 0; i != meshes.front()->attributeCount(); ++i) {
+        const VertexFormat format = meshes.front()->attributeFormat(i);
+        CORRADE_ASSERT(!isVertexFormatImplementationSpecific(format),
+            "MeshTools::concatenate(): attribute" << i << "of the first mesh has an implementation-specific format" << reinterpret_cast<void*>(vertexFormatUnwrap(format)),
+            (Trade::MeshData{MeshPrimitive::Points, 0}));
+    }
+    #endif
 
     /* Calculate final attribute stride and offsets. Make a non-owning copy of
        the attribute data to avoid interleavedLayout() stealing the original
diff --git a/src/Magnum/MeshTools/Concatenate.h b/src/Magnum/MeshTools/Concatenate.h
index 4889db09d..af8167311 100644
--- a/src/Magnum/MeshTools/Concatenate.h
+++ b/src/Magnum/MeshTools/Concatenate.h
@@ -57,20 +57,21 @@ concatenated --- use @ref generateIndices() to turn them into
 @ref MeshPrimitive::Lines or @ref MeshPrimitive::Triangles first. The @p meshes
 array is expected to have at least one item.
 
-All attributes from the first mesh are taken; for each following mesh
-attributes present in the first are copied, superfluous attributes ignored and
-missing attributes zeroed out. Matching attributes are expected to have the
-same type, all meshes are expected to have the same primitive. The vertex data
-are concatenated in the same order as passed, with no duplicate removal.
-Returned instance vertex and index data flags always have both
-@ref Trade::DataFlag::Owned and @ref Trade::DataFlag::Mutable to guarante
-mutable access to particular parts of the concatenated mesh --- for example for
-applying transformations.
+All attributes from the first mesh are taken, expected to not have an
+implementation-specific format. For each following mesh attributes present in
+the first are copied, superfluous attributes ignored and missing attributes
+zeroed out. Matching attributes are expected to have the same type, all meshes
+are expected to have the same primitive. The vertex data are concatenated in
+the same order as passed, with no duplicate removal. Returned instance vertex
+and index data flags always have both @ref Trade::DataFlag::Owned and
+@ref Trade::DataFlag::Mutable to guarante mutable access to particular parts of
+the concatenated mesh --- for example for applying transformations.
 
 If an index buffer is needed, @ref MeshIndexType::UnsignedInt is always used.
 Call @ref compressIndices(const Trade::MeshData&, MeshIndexType) on the result
 to compress it to a smaller type, if desired.
-@see @ref concatenateInto(), @ref SceneTools::flattenMeshHierarchy2D(),
+@see @ref concatenateInto(), @ref isVertexFormatImplementationSpecific(),
+    @ref SceneTools::flattenMeshHierarchy2D(),
     @ref SceneTools::flattenMeshHierarchy3D()
 */
 MAGNUM_MESHTOOLS_EXPORT Trade::MeshData concatenate(Containers::ArrayView<const Containers::Reference<const Trade::MeshData>> meshes);
@@ -99,6 +100,13 @@ layout from @p destination is used, all vertex/index data are taken from
 template<template<class> class Allocator = Containers::ArrayAllocator> void concatenateInto(Trade::MeshData& destination, const Containers::ArrayView<const Containers::Reference<const Trade::MeshData>> meshes) {
     CORRADE_ASSERT(!meshes.empty(),
         "MeshTools::concatenateInto(): no meshes passed", );
+    #ifndef CORRADE_NO_ASSERT
+    for(std::size_t i = 0; i != destination.attributeCount(); ++i) {
+        const VertexFormat format = destination.attributeFormat(i);
+        CORRADE_ASSERT(!isVertexFormatImplementationSpecific(format),
+            "MeshTools::concatenateInto(): attribute" << i << "of the destination mesh has an implementation-specific format" << reinterpret_cast<void*>(vertexFormatUnwrap(format)), );
+    }
+    #endif
 
     std::pair<UnsignedInt, UnsignedInt> indexVertexCount = Implementation::concatenateIndexVertexCount(meshes);
 
diff --git a/src/Magnum/MeshTools/Test/ConcatenateTest.cpp b/src/Magnum/MeshTools/Test/ConcatenateTest.cpp
index d62204d01..cb60fcee0 100644
--- a/src/Magnum/MeshTools/Test/ConcatenateTest.cpp
+++ b/src/Magnum/MeshTools/Test/ConcatenateTest.cpp
@@ -50,6 +50,7 @@ struct ConcatenateTest: TestSuite::Tester {
     void concatenateInconsistentPrimitive();
     void concatenateInconsistentAttributeFormat();
     void concatenateInconsistentAttributeArraySize();
+    void concatenateImplementationSpecificVertexFormat();
     void concatenateIntoNoMeshes();
 };
 
@@ -68,6 +69,7 @@ ConcatenateTest::ConcatenateTest() {
               &ConcatenateTest::concatenateInconsistentPrimitive,
               &ConcatenateTest::concatenateInconsistentAttributeFormat,
               &ConcatenateTest::concatenateInconsistentAttributeArraySize,
+              &ConcatenateTest::concatenateImplementationSpecificVertexFormat,
               &ConcatenateTest::concatenateIntoNoMeshes});
 }
 
@@ -637,6 +639,36 @@ void ConcatenateTest::concatenateInconsistentAttributeArraySize() {
         "MeshTools::concatenateInto(): expected array size 5 for attribute 2 (Trade::MeshAttribute::Custom(42)) but got 4 in mesh 3 attribute 1\n");
 }
 
+void ConcatenateTest::concatenateImplementationSpecificVertexFormat() {
+    #ifdef CORRADE_NO_ASSERT
+    CORRADE_SKIP("CORRADE_NO_ASSERT defined, can't test assertions");
+    #endif
+
+    /* Things are a bit duplicated to test correct numbering */
+    Trade::MeshData a{MeshPrimitive::Lines, nullptr, {
+        Trade::MeshAttributeData{Trade::MeshAttribute::Position,
+            VertexFormat::Vector3, nullptr},
+        Trade::MeshAttributeData{Trade::MeshAttribute::Normal,
+            VertexFormat::Vector3, nullptr},
+        Trade::MeshAttributeData{Trade::MeshAttribute::Color,
+            vertexFormatWrap(0xcaca), nullptr}
+    }};
+    Trade::MeshData b{MeshPrimitive::Lines, nullptr, {
+        Trade::MeshAttributeData{Trade::MeshAttribute::Position,
+            VertexFormat::Vector3, nullptr},
+        Trade::MeshAttributeData{Trade::MeshAttribute::Normal,
+            VertexFormat::Vector3, nullptr}
+    }};
+
+    std::ostringstream out;
+    Error redirectError{&out};
+    MeshTools::concatenate({a, b});
+    MeshTools::concatenateInto(a, {b});
+    CORRADE_COMPARE(out.str(),
+        "MeshTools::concatenate(): attribute 2 of the first mesh has an implementation-specific format 0xcaca\n"
+        "MeshTools::concatenateInto(): attribute 2 of the destination mesh has an implementation-specific format 0xcaca\n");
+}
+
 void ConcatenateTest::concatenateIntoNoMeshes() {
     #ifdef CORRADE_NO_ASSERT
     CORRADE_SKIP("CORRADE_NO_ASSERT defined, can't test assertions");