diff --git a/dlls/uxtheme/msstyles.c b/dlls/uxtheme/msstyles.c
index 7d3ee72efe8..9e5a79a1c69 100644
--- a/dlls/uxtheme/msstyles.c
+++ b/dlls/uxtheme/msstyles.c
@@ -452,6 +452,36 @@ static PTHEME_CLASS MSSTYLES_AddClass(PTHEME_FILE tf, LPCWSTR pszAppName, LPCWST
     return cur;
 }
 
+/***********************************************************************
+ *      MSSTYLES_FindPart
+ *
+ * Find a part
+ *
+ * PARAMS
+ *     tc                  Class to search
+ *     iPartId             Part ID to find
+ *
+ * RETURNS
+ *  The part found, or NULL
+ */
+PTHEME_PARTSTATE MSSTYLES_FindPart(PTHEME_CLASS tc, int iPartId)
+{
+    PTHEME_PARTSTATE cur = tc->partstate;
+
+    while (cur)
+    {
+        if (cur->iPartId == iPartId)
+            return cur;
+
+        cur = cur->next;
+    }
+
+    if (tc->overrides)
+        return MSSTYLES_FindPart(tc->overrides, iPartId);
+
+    return NULL;
+}
+
 /***********************************************************************
  *      MSSTYLES_FindPartState
  *
diff --git a/dlls/uxtheme/msstyles.h b/dlls/uxtheme/msstyles.h
index 12292cefae4..67f81315d7a 100644
--- a/dlls/uxtheme/msstyles.h
+++ b/dlls/uxtheme/msstyles.h
@@ -95,6 +95,7 @@ BOOL MSSTYLES_LookupEnum(LPCWSTR pszValueName, int dwEnum, int *dwValue) DECLSPE
 BOOL MSSTYLES_LookupPartState(LPCWSTR pszClass, LPCWSTR pszPart, LPCWSTR pszState, int *iPartId, int *iStateId) DECLSPEC_HIDDEN;
 PUXINI_FILE MSSTYLES_GetThemeIni(PTHEME_FILE tf) DECLSPEC_HIDDEN;
 UINT MSSTYLES_GetThemeDPI(PTHEME_CLASS tc) DECLSPEC_HIDDEN;
+PTHEME_PARTSTATE MSSTYLES_FindPart(PTHEME_CLASS tc, int iPartId) DECLSPEC_HIDDEN;
 PTHEME_PARTSTATE MSSTYLES_FindPartState(PTHEME_CLASS tc, int iPartId, int iStateId, PTHEME_CLASS *tcNext) DECLSPEC_HIDDEN;
 PTHEME_PROPERTY MSSTYLES_FindProperty(PTHEME_CLASS tc, int iPartId, int iStateId, int iPropertyPrimitive, int iPropertyId) DECLSPEC_HIDDEN;
 PTHEME_PROPERTY MSSTYLES_FindMetric(int iPropertyPrimitive, int iPropertyId) DECLSPEC_HIDDEN;
diff --git a/dlls/uxtheme/system.c b/dlls/uxtheme/system.c
index 8333d6b99ce..908451f0fe8 100644
--- a/dlls/uxtheme/system.c
+++ b/dlls/uxtheme/system.c
@@ -809,9 +809,9 @@ BOOL WINAPI IsThemePartDefined(HTHEME hTheme, int iPartId, int iStateId)
         SetLastError(E_HANDLE);
         return FALSE;
     }
-    if(MSSTYLES_FindPartState(hTheme, iPartId, iStateId, NULL))
-        return TRUE;
-    return FALSE;
+
+    SetLastError(NO_ERROR);
+    return !iStateId && MSSTYLES_FindPart(hTheme, iPartId);
 }
 
 /***********************************************************************
diff --git a/dlls/uxtheme/tests/system.c b/dlls/uxtheme/tests/system.c
index 59631f01fe9..dd118f5ab37 100644
--- a/dlls/uxtheme/tests/system.c
+++ b/dlls/uxtheme/tests/system.c
@@ -300,7 +300,6 @@ static void test_IsThemePartDefined(void)
         int state;
         BOOL defined;
         DWORD error;
-        BOOL todo;
     }
     tests[] =
     {
@@ -311,7 +310,7 @@ static void test_IsThemePartDefined(void)
         {L"Button", BP_PUSHBUTTON, PBS_NORMAL, FALSE, NO_ERROR},
         {L"Button", BP_PUSHBUTTON, PBS_DEFAULTED_ANIMATING, FALSE, NO_ERROR},
         {L"Button", BP_PUSHBUTTON, PBS_DEFAULTED_ANIMATING + 1, FALSE, NO_ERROR},
-        {L"Edit", EP_EDITTEXT, 0, TRUE, NO_ERROR, TRUE},
+        {L"Edit", EP_EDITTEXT, 0, TRUE, NO_ERROR},
         {L"Edit", EP_EDITTEXT, ETS_NORMAL, FALSE, NO_ERROR},
         {L"Edit", EP_EDITTEXT, ETS_FOCUSED, FALSE, NO_ERROR},
     };
@@ -337,9 +336,7 @@ static void test_IsThemePartDefined(void)
         SetLastError(0xdeadbeef);
         ret = IsThemePartDefined(theme, tests[i].part, tests[i].state);
         error = GetLastError();
-        todo_wine_if(tests[i].todo)
         ok(ret == tests[i].defined, "Expected %d.\n", tests[i].defined);
-        todo_wine_if(error == 0xdeadbeef && tests[i].error == NO_ERROR)
         ok(error == tests[i].error, "Expected %#x, got %#x.\n", tests[i].error, error);
 
         if (theme)
@@ -589,12 +586,8 @@ static void test_OpenThemeData(void)
     SetLastError(0xdeadbeef);
     bTPDefined = IsThemePartDefined(hTheme, 0 , 0);
     todo_wine
-    {
-        ok( bTPDefined == FALSE, "Expected FALSE\n");
-        ok( GetLastError() == ERROR_SUCCESS,
-            "Expected ERROR_SUCCESS, got 0x%08x\n",
-            GetLastError());
-    }
+    ok( bTPDefined == FALSE, "Expected FALSE\n" );
+    ok( GetLastError() == ERROR_SUCCESS, "Expected ERROR_SUCCESS, got 0x%08x\n", GetLastError() );
 
     DestroyWindow(hWnd);
 }