diff --git a/lib/tokenlist.cpp b/lib/tokenlist.cpp
index 399d0e5c4d7..15cad7fadce 100644
--- a/lib/tokenlist.cpp
+++ b/lib/tokenlist.cpp
@@ -45,14 +45,7 @@
 
 #include <simplecpp.h>
 
-//#define N_ASSERT_LANG
-
-#ifndef N_ASSERT_LANG
-#include <cassert>
-#define ASSERT_LANG(x) assert(x)
-#else
-#define ASSERT_LANG(x)
-#endif
+#define ASSERT_LANG(x) do { if (!(x)) throw InternalError(nullptr, __FILE__ ":" + std::to_string(__LINE__) + ": Assertion " #x " failed"); } while (0)
 
 // How many compileExpression recursions are allowed?
 // For practical code this could be endless. But in some special torture test
@@ -2302,6 +2295,7 @@ void TokenList::setLang(Standards::Language lang, bool force)
     ASSERT_LANG(lang != Standards::Language::None);
     if (!force)
     {
+        // cppcheck-suppress premium-misra-cpp-2023-19.3.3; this is a false positive, will be fixed
         ASSERT_LANG(mLang == Standards::Language::None);
     }
 
diff --git a/test/testtokenlist.cpp b/test/testtokenlist.cpp
index f98a0ea2dd2..6bda24d8afe 100644
--- a/test/testtokenlist.cpp
+++ b/test/testtokenlist.cpp
@@ -49,6 +49,7 @@ class TestTokenList : public TestFixture {
         TEST_CASE(isKeyword);
         TEST_CASE(notokens);
         TEST_CASE(ast1);
+        TEST_CASE(setLangInternalError);
     }
 
     // inspired by #5895
@@ -191,6 +192,12 @@ class TestTokenList : public TestFixture {
         }
         tokenlist.createAst(); // do not crash
     }
+
+    void setLangInternalError() const {
+        TokenList tokenList(nullptr);
+        tokenList.setLang(Standards::Language::C, true);
+        ASSERT_THROW_INTERNAL(tokenList.setLang(Standards::Language::CPP, false), InternalError::INTERNAL);
+    }
 };
 
 REGISTER_TEST(TestTokenList)