diff --git a/lib/tokenlist.cpp b/lib/tokenlist.cpp
index a76493139c7..26b24d649c8 100644
--- a/lib/tokenlist.cpp
+++ b/lib/tokenlist.cpp
@@ -102,7 +102,7 @@ int TokenList::appendFileIfNew(std::string fileName)
     if (it != mFiles.cend())
         return static_cast<int>(std::distance(mFiles.cbegin(), it));
 
-    assert(mTokensFrontBack->front == nullptr); // has no effect if tokens have already been created
+    assert(mSettings.clang || mTokensFrontBack->front == nullptr); // has no effect if tokens have already been created
 
     // The "mFiles" vector remembers what files have been tokenized..
     mFiles.push_back(std::move(fileName));
diff --git a/test/cli/clang-import_test.py b/test/cli/clang-import_test.py
index e4ec19a5ada..da5bb2f3af7 100644
--- a/test/cli/clang-import_test.py
+++ b/test/cli/clang-import_test.py
@@ -128,6 +128,21 @@ def test_log(tmpdir):
     assert_cppcheck(args, ec_exp=0, err_exp=[], out_exp=out_lines)
 
 
+def test_include(tmp_path):
+    test_file = tmp_path / 'test.c'
+    with open(test_file, 'wt') as f:
+        f.write('#include "test.h"')
+
+    with open(tmp_path / 'test.h', 'wt') as f:
+        f.write('int x;\n')
+
+    exitcode, stdout, stderr = cppcheck(['-q', '--clang', '--debug', str(test_file)])
+    assert exitcode == 0, stderr if not stdout else stdout
+    # the number of empty lines after "##file" depends on the builtin declarations in the clang AST dump
+    assert '##file {}\n'.format(tmp_path / 'test.h') in stdout, stdout
+    assert '\n1: int x@var1 ;\n' in stdout, stdout
+
+
 def test_warning(tmpdir):  # #12424
     test_file = os.path.join(tmpdir, 'test_2')
     with open(test_file, 'wt') as f:
diff --git a/test/testclangimport.cpp b/test/testclangimport.cpp
index 229e4c3c982..d307cf201de 100644
--- a/test/testclangimport.cpp
+++ b/test/testclangimport.cpp
@@ -116,6 +116,7 @@ class TestClangImport : public TestFixture {
         TEST_CASE(vardecl5);
         TEST_CASE(vardecl6);
         TEST_CASE(vardecl7);
+        TEST_CASE(vardeclInHeader);
         TEST_CASE(whileStmt1);
         TEST_CASE(whileStmt2);
 
@@ -1040,6 +1041,15 @@ class TestClangImport : public TestFixture {
         ASSERT_EQUALS("void * * start@1 ;", parse(clang));
     }
 
+    void vardeclInHeader() {
+        // a new file is seen after tokens have been created
+        const char clang[] = "|-VarDecl 0x32b8aa0 <1.c:1:1, col:5> col:5 a 'int'\n"
+                             "`-VarDecl 0x32b8b78 <1.h:1:1, col:5> col:5 b 'int'";
+
+        ASSERT_EQUALS("int a@1 ; int b@2 ;",
+                      parse(clang));
+    }
+
     void whileStmt1() {
         const char clang[] = "`-FunctionDecl 0x3d45b18 <1.c:1:1, line:3:1> line:1:6 foo 'void ()'\n"
                              "  `-CompoundStmt 0x3d45c48 <col:12, line:3:1>\n"