diff --git a/src/amdis/common/FieldMatVec.inc.hpp b/src/amdis/common/FieldMatVec.inc.hpp
index 8e57a3ea506ba0386e70145be9426d01d8ca3604..40d8dbe696104d35966b265267e269f7c52fa626 100644
--- a/src/amdis/common/FieldMatVec.inc.hpp
+++ b/src/amdis/common/FieldMatVec.inc.hpp
@@ -50,7 +50,7 @@ namespace MatVec {
     std::enable_if_t<IsMatrix<Mat>::value && IsVector<Vec>::value, int>>
   auto multiplies(Mat const& mat, Vec const& vec)
   {
-    static_assert(Mat::cols == Vec::dimension, "");
+    static_assert(int(Mat::cols) == int(Vec::dimension), "");
     using T = std::common_type_t<typename FieldTraits<Vec>::field_type, typename FieldTraits<Mat>::field_type>;
     FieldVector<T,Mat::rows> y;
     mat.mv(vec, y);
@@ -62,7 +62,7 @@ namespace MatVec {
     std::enable_if_t<IsVector<Vec>::value && IsMatrix<Mat>::value, int>>
   auto multiplies(Vec const& vec, Mat const& mat)
   {
-    static_assert(Mat::rows == Vec::dimension, "");
+    static_assert(int(Mat::rows) == int(Vec::dimension), "");
     using T = std::common_type_t<typename FieldTraits<Vec>::field_type, typename FieldTraits<Mat>::field_type>;
     FieldVector<T,Mat::cols> y;
     mat.mtv(vec, y);