diff --git a/include/wx/string.h b/include/wx/string.h
index 4591e1b075..03c21a7acf 100644
--- a/include/wx/string.h
+++ b/include/wx/string.h
@@ -2669,7 +2669,7 @@ public:
 
   wxString& assign(const char *sz, size_t n)
   {
-      wxSTRING_SET_CACHED_LENGTH(n);
+      wxSTRING_INVALIDATE_CACHE();
 
       SubstrBufFromMB str(ImplStr(sz, n));
       m_impl.assign(str.data, str.len);
diff --git a/tests/strings/strings.cpp b/tests/strings/strings.cpp
index 879fab7907..13904976ac 100644
--- a/tests/strings/strings.cpp
+++ b/tests/strings/strings.cpp
@@ -192,6 +192,12 @@ void StringTestCase::Constructors()
 
     CPPUNIT_ASSERT_EQUAL( 0, wxString(wxString(), 17).length() );
 
+    // This string has 3 characters (<h>, <e'> and <l>), not 4!
+    wxString s3("h\xc3\xa9llo", 4);
+    CPPUNIT_ASSERT_EQUAL( 3, s3.length() );
+    CPPUNIT_ASSERT_EQUAL( 'l', (char)s3[2] );
+
+
     static const char *s = "?really!";
     const char *start = wxStrchr(s, 'r');
     const char *end = wxStrchr(s, '!');
@@ -219,6 +225,9 @@ void StringTestCase::StaticConstructors()
     CPPUNIT_ASSERT_EQUAL( "Hello", wxString::FromUTF8("Hello", 5) );
     CPPUNIT_ASSERT_EQUAL( "Hello", wxString::FromUTF8("Hello") );
 
+    CPPUNIT_ASSERT_EQUAL( 2, wxString::FromUTF8("h\xc3\xa9llo", 3).length() );
+
+
     //CPPUNIT_ASSERT_EQUAL( 1, wxString::FromUTF8("", 1).length() );
 }