diff --git a/rostests/winetests/user32/listbox.c b/rostests/winetests/user32/listbox.c
index 8e3fbcd34a1..d99a82c8b8e 100644
--- a/rostests/winetests/user32/listbox.c
+++ b/rostests/winetests/user32/listbox.c
@@ -1617,6 +1617,83 @@ static void test_missing_lbuttonup( void )
     DestroyWindow(parent);
 }
 
+static void test_extents(void)
+{
+    HWND listbox, parent;
+    DWORD res;
+    SCROLLINFO sinfo;
+    BOOL br;
+
+    parent = create_parent();
+
+    listbox = create_listbox(WS_CHILD | WS_VISIBLE, parent);
+
+    res = SendMessageA(listbox, LB_GETHORIZONTALEXTENT, 0, 0);
+    ok(res == 0, "Got wrong initial horizontal extent: %u\n", res);
+
+    sinfo.cbSize = sizeof(sinfo);
+    sinfo.fMask = SIF_RANGE;
+    br = GetScrollInfo(listbox, SB_HORZ, &sinfo);
+    ok(br == TRUE, "GetScrollInfo failed\n");
+    ok(sinfo.nMin == 0, "got wrong min: %u\n", sinfo.nMin);
+    ok(sinfo.nMax == 100, "got wrong max: %u\n", sinfo.nMax);
+
+    SendMessageA(listbox, LB_SETHORIZONTALEXTENT, 64, 0);
+
+    res = SendMessageA(listbox, LB_GETHORIZONTALEXTENT, 0, 0);
+    ok(res == 64, "Got wrong horizontal extent: %u\n", res);
+
+    sinfo.cbSize = sizeof(sinfo);
+    sinfo.fMask = SIF_RANGE;
+    br = GetScrollInfo(listbox, SB_HORZ, &sinfo);
+    ok(br == TRUE, "GetScrollInfo failed\n");
+    ok(sinfo.nMin == 0, "got wrong min: %u\n", sinfo.nMin);
+    ok(sinfo.nMax == 100, "got wrong max: %u\n", sinfo.nMax);
+
+    DestroyWindow(listbox);
+
+
+    listbox = create_listbox(WS_CHILD | WS_VISIBLE | WS_HSCROLL, parent);
+
+    res = SendMessageA(listbox, LB_GETHORIZONTALEXTENT, 0, 0);
+    ok(res == 0, "Got wrong initial horizontal extent: %u\n", res);
+
+    sinfo.cbSize = sizeof(sinfo);
+    sinfo.fMask = SIF_RANGE;
+    br = GetScrollInfo(listbox, SB_HORZ, &sinfo);
+    ok(br == TRUE, "GetScrollInfo failed\n");
+    ok(sinfo.nMin == 0, "got wrong min: %u\n", sinfo.nMin);
+    ok(sinfo.nMax == 100, "got wrong max: %u\n", sinfo.nMax);
+
+    SendMessageA(listbox, LB_SETHORIZONTALEXTENT, 64, 0);
+
+    res = SendMessageA(listbox, LB_GETHORIZONTALEXTENT, 0, 0);
+    ok(res == 64, "Got wrong horizontal extent: %u\n", res);
+
+    sinfo.cbSize = sizeof(sinfo);
+    sinfo.fMask = SIF_RANGE;
+    br = GetScrollInfo(listbox, SB_HORZ, &sinfo);
+    ok(br == TRUE, "GetScrollInfo failed\n");
+    ok(sinfo.nMin == 0, "got wrong min: %u\n", sinfo.nMin);
+    ok(sinfo.nMax == 63, "got wrong max: %u\n", sinfo.nMax);
+
+    SendMessageA(listbox, LB_SETHORIZONTALEXTENT, 0, 0);
+
+    res = SendMessageA(listbox, LB_GETHORIZONTALEXTENT, 0, 0);
+    ok(res == 0, "Got wrong horizontal extent: %u\n", res);
+
+    sinfo.cbSize = sizeof(sinfo);
+    sinfo.fMask = SIF_RANGE;
+    br = GetScrollInfo(listbox, SB_HORZ, &sinfo);
+    ok(br == TRUE, "GetScrollInfo failed\n");
+    ok(sinfo.nMin == 0, "got wrong min: %u\n", sinfo.nMin);
+    ok(sinfo.nMax == 0, "got wrong max: %u\n", sinfo.nMax);
+
+    DestroyWindow(listbox);
+
+    DestroyWindow(parent);
+}
+
 START_TEST(listbox)
 {
   const struct listbox_test SS =
@@ -1698,4 +1775,5 @@ START_TEST(listbox)
   test_set_count();
   test_GetListBoxInfo();
   test_missing_lbuttonup();
+  test_extents();
 }