diff --git a/src/sequence_diagram/visitor/translation_unit_visitor.cc b/src/sequence_diagram/visitor/translation_unit_visitor.cc
index dae80f38..7845a810 100644
--- a/src/sequence_diagram/visitor/translation_unit_visitor.cc
+++ b/src/sequence_diagram/visitor/translation_unit_visitor.cc
@@ -518,7 +518,8 @@ bool translation_unit_visitor::TraverseLambdaExpr(clang::LambdaExpr *expr)
 
 bool translation_unit_visitor::TraverseCallExpr(clang::CallExpr *expr)
 {
-    if (source_manager().isInSystemHeader(expr->getSourceRange().getBegin()))
+    if (!config().include_system_headers() &&
+        source_manager().isInSystemHeader(expr->getSourceRange().getBegin()))
         return true;
 
     LOG_TRACE("Entering call expression at {}",
@@ -541,7 +542,8 @@ bool translation_unit_visitor::TraverseCallExpr(clang::CallExpr *expr)
 bool translation_unit_visitor::TraverseCUDAKernelCallExpr(
     clang::CUDAKernelCallExpr *expr)
 {
-    if (source_manager().isInSystemHeader(expr->getSourceRange().getBegin()))
+    if (!config().include_system_headers() &&
+        source_manager().isInSystemHeader(expr->getSourceRange().getBegin()))
         return true;
 
     LOG_TRACE("Entering CUDA kernel call expression at {}",
@@ -564,7 +566,8 @@ bool translation_unit_visitor::TraverseCUDAKernelCallExpr(
 bool translation_unit_visitor::TraverseCXXMemberCallExpr(
     clang::CXXMemberCallExpr *expr)
 {
-    if (source_manager().isInSystemHeader(expr->getSourceRange().getBegin()))
+    if (!config().include_system_headers() &&
+        source_manager().isInSystemHeader(expr->getSourceRange().getBegin()))
         return true;
 
     LOG_TRACE("Entering member call expression at {}",
diff --git a/tests/t20002/t20002.cc b/tests/t20002/t20002.cc
index 9888c599..e225f605 100644
--- a/tests/t20002/t20002.cc
+++ b/tests/t20002/t20002.cc
@@ -1,7 +1,3 @@
-#include <algorithm>
-#include <numeric>
-#include <vector>
-
 namespace clanguml {
 namespace t20002 {
 
diff --git a/tests/t20055/.clang-uml b/tests/t20055/.clang-uml
index a31a348d..a83d995f 100644
--- a/tests/t20055/.clang-uml
+++ b/tests/t20055/.clang-uml
@@ -10,6 +10,7 @@ diagrams:
           - clanguml::t20055::ns2
         elements:
           - clanguml::t20055::ns1::B
+          - clanguml::t20055::ns1::d()
     using_namespace: clanguml::t20055
     from:
       - function: "clanguml::t20055::ns2::tmain()"
\ No newline at end of file
diff --git a/tests/t20055/t20055.cc b/tests/t20055/t20055.cc
index f30432bd..3ff58cee 100644
--- a/tests/t20055/t20055.cc
+++ b/tests/t20055/t20055.cc
@@ -2,13 +2,19 @@ namespace clanguml {
 namespace t20055 {
 namespace ns1 {
 
+void d() { }
+
 struct A {
     void a() { }
 };
 
 struct B {
     A a;
-    void b() { a.a(); }
+    void b()
+    {
+        a.a();
+        d();
+    }
 };
 
 } // namespace ns1
diff --git a/tests/t20055/test_case.h b/tests/t20055/test_case.h
index e89a53c6..36807d3f 100644
--- a/tests/t20055/test_case.h
+++ b/tests/t20055/test_case.h
@@ -30,6 +30,7 @@ TEST_CASE("t20055")
                 //
                 {{"ns2", "tmain()"}, {"ns2", "C"}, "c()"},
                 {{"ns2", "C"}, {"ns1", "B"}, "b()"},
+                {{"ns1", "B"}, {"ns1", "d()"}, ""},
                 {{"ns2", "C"}, {"ns2", "f()"}, ""}
                 //
             }));