diff --git a/rostests/apitests/user32api/testlist.c b/rostests/apitests/user32api/testlist.c
index f77cb30b1c6..ce0d337d909 100644
--- a/rostests/apitests/user32api/testlist.c
+++ b/rostests/apitests/user32api/testlist.c
@@ -1,23 +1,27 @@
 #ifndef _USER32TESTLIST_H
 #define _USER32TESTLIST_H
 
+#define ARRAY_SIZE(x)   (sizeof(x)/sizeof(x[0]))
+
 #include "user32api.h"
 
 /* include the tests */
 #include "tests/ScrollDC.c"
 #include "tests/ScrollWindowEx.c"
+#include "tests/RealGetWindowClass.c"
 
 /* The List of tests */
 TESTENTRY TestList[] =
 {
-	{ L"ScrollDC", Test_ScrollDC },
-	{ L"ScrollWindowEx", Test_ScrollWindowEx }
+    { L"ScrollDC", Test_ScrollDC },
+    { L"ScrollWindowEx", Test_ScrollWindowEx },
+    { L"RealGetWindowClass", Test_RealGetWindowClass },
 };
 
 /* The function that gives us the number of tests */
 INT NumTests(void)
 {
-	return sizeof(TestList) / sizeof(TESTENTRY);
+    return ARRAY_SIZE(TestList);
 }
 
 #endif /* _USER32TESTLIST_H */
diff --git a/rostests/apitests/user32api/tests/RealGetWindowClass.c b/rostests/apitests/user32api/tests/RealGetWindowClass.c
new file mode 100644
index 00000000000..25d94dc74b9
--- /dev/null
+++ b/rostests/apitests/user32api/tests/RealGetWindowClass.c
@@ -0,0 +1,119 @@
+#include "../user32api.h"
+
+typedef struct _TestData
+{
+    BOOL    OverrideWndProc;            /* TRUE if lpfnWndProc should be overridden */
+    LPCSTR  ClassName;                  /* Name of the new class to register */
+    DWORD   WndExtra;                   /* Remove these WNDCLASS::cbWndExtra flags */
+    BOOL    ExpectsHwnd;                /* TRUE if a HWND should be created to run tests on */
+    LPCSTR  ExpectedClassNameBefore;    /* Expected class name before any dialog function is called */
+    LPCSTR  ExpectedClassNameAfter;     /* Expected class name after any dialog function is called */
+} TestData;
+
+static TestData RealClassTestData[] =
+{
+    {
+        TRUE,
+        "OverrideWndProc_with_DLGWINDOWEXTRA_TRUE",
+        0,
+        TRUE,
+        "OverrideWndProc_with_DLGWINDOWEXTRA_TRUE",
+        "#32770",
+    },
+    {
+        TRUE,
+        "OverrideWndProc_without_DLGWINDOWEXTRA_TRUE",
+        DLGWINDOWEXTRA,
+        TRUE,
+        "OverrideWndProc_without_DLGWINDOWEXTRA_TRUE",
+        "OverrideWndProc_without_DLGWINDOWEXTRA_TRUE",
+    },
+    {
+        FALSE,
+        "DefaultWndProc_with_DLGWINDOWEXTRA_FALSE",
+        0,
+        TRUE,
+        "#32770",
+        "#32770",
+    },
+    {
+        FALSE,
+        "DefaultWndProc_without_DLGWINDOWEXTRA_FALSE",
+        DLGWINDOWEXTRA,
+        FALSE,
+        "N/A",
+        "N/A",
+    },
+};
+
+INT
+Test_RealGetWindowClass(PTESTINFO pti)
+{
+    int testNo;
+    UINT Result;
+    CHAR Buffer[1024];
+
+    Result = RealGetWindowClass( NULL, Buffer, ARRAY_SIZE(Buffer) );
+    TEST(Result == 0);
+    TEST(GetLastError() == ERROR_INVALID_WINDOW_HANDLE);
+
+    for (testNo = 0; testNo < ARRAY_SIZE(RealClassTestData); testNo++)
+    {
+        ATOM atom;
+        WNDCLASSA cls;
+        HWND hWnd;
+
+        /* Register classes, "derived" from built-in dialog, with and without the DLGWINDOWEXTRA flag set */
+        GetClassInfoA(0, "#32770", &cls);
+        if (RealClassTestData[testNo].OverrideWndProc)
+            cls.lpfnWndProc = DefWindowProcA;
+        cls.lpszClassName = RealClassTestData[testNo].ClassName;
+        cls.cbWndExtra &= ~RealClassTestData[testNo].WndExtra;
+        atom = RegisterClassA (&cls);
+        ASSERT(atom != 0);
+
+        /* Create a window */
+        hWnd = CreateWindowEx( WS_EX_LEFT | WS_EX_LTRREADING | WS_EX_RIGHTSCROLLBAR |
+                               WS_EX_DLGMODALFRAME | WS_EX_WINDOWEDGE | WS_EX_CONTROLPARENT | WS_EX_APPWINDOW,
+                               RealClassTestData[testNo].ClassName,
+                               RealClassTestData[testNo].ClassName,
+                               WS_POPUPWINDOW | WS_CLIPSIBLINGS | WS_DLGFRAME | WS_OVERLAPPED |
+                               WS_MINIMIZEBOX | WS_MAXIMIZEBOX | DS_3DLOOK | DS_SETFONT | DS_MODALFRAME,
+                               CW_USEDEFAULT, CW_USEDEFAULT, 100, 100,
+                               NULL, NULL, g_hInstance, 0);
+
+        /* Do we expect a HWND at all? */
+        if (RealClassTestData[testNo].ExpectsHwnd)
+        {
+            TEST(hWnd != NULL);
+
+            if (hWnd != NULL)
+            {
+                /* Get the "real" class name */
+                Result = RealGetWindowClass( hWnd, Buffer, ARRAY_SIZE(Buffer) );
+                printf("Buffer: %s\nExpectedClassNameBefore(%d): %s\n", Buffer, testNo, RealClassTestData[testNo].ExpectedClassNameBefore);
+                TEST( Result != 0 );
+                TEST( strcmp( Buffer, RealClassTestData[testNo].ExpectedClassNameBefore ) == 0 );
+
+                /* Call a function that requires a dialog window */
+                DefDlgProcA( hWnd, DM_SETDEFID, IDCANCEL, 0 );
+
+                /* Get the "real" class name again */
+                Result = RealGetWindowClass( hWnd, Buffer, ARRAY_SIZE(Buffer) );
+                printf("Buffer: %s\nExpectedClassNameAfter(%d): %s\n", Buffer, testNo, RealClassTestData[testNo].ExpectedClassNameAfter);
+                TEST( Result != 0 );
+                TEST( strcmp( Buffer, RealClassTestData[testNo].ExpectedClassNameAfter ) == 0 );
+            }
+        }
+        else
+        {
+            TEST(hWnd == NULL);
+        }
+
+        /* Cleanup */
+        DestroyWindow(hWnd);
+        UnregisterClass(RealClassTestData[testNo].ClassName, g_hInstance);
+    }
+
+    return APISTATUS_NORMAL;
+}