diff --git a/cpp/find_warnings.py b/cpp/find_warnings.py
index 35e05b9..b7e11b6 100644
--- a/cpp/find_warnings.py
+++ b/cpp/find_warnings.py
@@ -182,8 +182,7 @@ def _read_and_parse_includes(self):
                     module = self._get_module(node)
                     filename = module.filename
                     _, ext = os.path.splitext(filename)
-                    if ext.lower() != '.hxx':
-                        included_files[filename] = node, module
+                    included_files[filename] = node, module
                 if is_cpp_file(filename):
                     self._add_warning(
                         "should not #include C++ source file '{}'".format(
diff --git a/test/a.hxx b/test/a.hxx
new file mode 100644
index 0000000..c048748
--- /dev/null
+++ b/test/a.hxx
@@ -0,0 +1,8 @@
+#ifndef _A_H_
+#define _A_H_
+
+#include "b.hxx"
+
+void myFunc(int a);
+
+#endif
diff --git a/test/b.hxx b/test/b.hxx
new file mode 100644
index 0000000..c234721
--- /dev/null
+++ b/test/b.hxx
@@ -0,0 +1,14 @@
+#ifndef _B_H_
+#define _B_H_
+
+namespace Name1 {
+class ABC {
+public:
+  ABC(): int1(0) {}
+  int getInt() { return int1; }
+private:
+  int int1;
+};
+}
+
+#endif
diff --git a/test/expected.txt b/test/expected.txt
index 525f5dd..03bc172 100644
--- a/test/expected.txt
+++ b/test/expected.txt
@@ -1,3 +1,4 @@
+test/a.hxx:4: 'b.hxx' does not need to be #included
 test/baz.h:1: 'bar.h' does not need to be #included; use a forward declaration instead
 test/baz.h:2: 'bar_bis.h' does not need to be #included; use a forward declaration instead
 test/cxx.cxx:1: 'cxx' not found in any directly #included header
@@ -18,6 +19,7 @@ test/foo.h:87: 'string' already #included on line 3
 test/foo.h:113: 'not-used.h' does not need to be #included
 test/foo.h:150: 'AR' not used
 test/foo.h:221: unable to find 'dir//bar.h'
+test/foo.h:307: 'foo.hxx' does not need to be #included; use a forward declaration instead
 test/foo.h:234 'Colon' has virtual methods without a virtual dtor
 test/foo.h:20: static data 'd'
 test/foo.h:101: static data 'ptof'