diff --git a/dlls/wsdapi/tests/xml.c b/dlls/wsdapi/tests/xml.c
index 4af81af49c0..fd8ac03831f 100644
--- a/dlls/wsdapi/tests/xml.c
+++ b/dlls/wsdapi/tests/xml.c
@@ -194,8 +194,97 @@ static void AddChild_tests(void)
     WSDFreeLinkedMemory(parent);
 }
 
+static void AddSibling_tests(void)
+{
+    WSDXML_ELEMENT *parent, *child1, *child2, *child3;
+    WSDXML_NAME parentName, child1Name, child2Name;
+    WSDXML_NAMESPACE ns;
+    WCHAR parentNameText[] = {'D','a','d',0};
+    WCHAR child1NameText[] = {'T','i','m',0};
+    WCHAR child2NameText[] = {'B','o','b',0};
+    static const WCHAR uri[] = {'h','t','t','p',':','/','/','t','e','s','t','.','t','e','s','t','/',0};
+    static const WCHAR prefix[] = {'t',0};
+    HRESULT hr;
+
+    /* Test invalid values */
+    hr = WSDXMLAddSibling(NULL, NULL);
+    ok(hr == E_INVALIDARG, "WSDXMLAddSibling failed with %08x\n", hr);
+
+    hr = WSDXMLAddSibling(child1, NULL);
+    ok(hr == E_INVALIDARG, "WSDXMLAddSibling failed with %08x\n", hr);
+
+    hr = WSDXMLAddSibling(NULL, child2);
+    ok(hr == E_INVALIDARG, "WSDXMLAddSibling failed with %08x\n", hr);
+
+    /* Populate structures */
+    ns.Uri = uri;
+    ns.PreferredPrefix = prefix;
+
+    parentName.LocalName = parentNameText;
+    parentName.Space = &ns;
+
+    child1Name.LocalName = child1NameText;
+    child1Name.Space = &ns;
+
+    child2Name.LocalName = child2NameText;
+    child2Name.Space = &ns;
+
+    /* Create some elements */
+    hr = WSDXMLBuildAnyForSingleElement(&parentName, NULL, &parent);
+    ok(hr == S_OK, "BuildAnyForSingleElement failed with %08x\n", hr);
+
+    hr = WSDXMLBuildAnyForSingleElement(&child1Name, child1NameText, &child1);
+    ok(hr == S_OK, "BuildAnyForSingleElement failed with %08x\n", hr);
+
+    hr = WSDXMLBuildAnyForSingleElement(&child2Name, NULL, &child2);
+    ok(hr == S_OK, "BuildAnyForSingleElement failed with %08x\n", hr);
+
+    hr = WSDXMLBuildAnyForSingleElement(&child2Name, NULL, &child3);
+    ok(hr == S_OK, "BuildAnyForSingleElement failed with %08x\n", hr);
+
+    /* Add child1 to parent */
+    hr = WSDXMLAddChild(parent, child1);
+    ok(hr == S_OK, "WSDXMLAddChild failed with %08x\n", hr);
+
+    ok(parent->Node.Parent == NULL, "parent->Node.Parent == %p\n", parent->Node.Parent);
+    ok(parent->FirstChild == (WSDXML_NODE *)child1, "parent->FirstChild == %p\n", parent->FirstChild);
+    ok(parent->Node.Next == NULL, "parent->Node.Next == %p\n", parent->Node.Next);
+    ok(child1->Node.Parent == parent, "child1->Node.Parent == %p\n", child1->Node.Parent);
+    ok(child1->FirstChild != NULL, "child1->FirstChild == NULL\n");
+    ok(child1->FirstChild->Type == TextType, "child1->FirstChild.Type == %d\n", child1->FirstChild->Type);
+    ok(child1->Node.Next == NULL, "child1->Node.Next == %p\n", child1->Node.Next);
+    ok(child2->Node.Parent == NULL, "child2->Node.Parent == %p\n", child2->Node.Parent);
+    ok(child2->FirstChild == NULL, "child2->FirstChild == %p\n", child2->FirstChild);
+    ok(child2->Node.Next == NULL, "child2->Node.Next == %p\n", child2->Node.Next);
+
+    /* Try to add child2 as sibling of child1 */
+    hr = WSDXMLAddSibling(child1, child2);
+    ok(hr == S_OK, "WSDXMLAddSibling failed with %08x\n", hr);
+
+    ok(child1->Node.Parent == parent, "child1->Node.Parent == %p\n", child1->Node.Parent);
+    ok(child1->Node.Next == (WSDXML_NODE *)child2, "child1->Node.Next == %p\n", child1->Node.Next);
+    ok(child2->Node.Parent == parent, "child2->Node.Parent == %p\n", child2->Node.Parent);
+    ok(child2->Node.Next == NULL, "child2->Node.Next == %p\n", child2->Node.Next);
+    ok(parent->FirstChild == (WSDXML_NODE *)child1, "parent->FirstChild == %p\n", parent->FirstChild);
+
+    /* Try to add child3 as sibling of child1 */
+    hr = WSDXMLAddSibling(child1, child3);
+    ok(hr == S_OK, "WSDXMLAddSibling failed with %08x\n", hr);
+
+    ok(child1->Node.Parent == parent, "child1->Node.Parent == %p\n", child1->Node.Parent);
+    ok(child1->Node.Next == (WSDXML_NODE *)child2, "child1->Node.Next == %p\n", child1->Node.Next);
+    ok(child2->Node.Parent == parent, "child2->Node.Parent == %p\n", child2->Node.Parent);
+    ok(child2->Node.Next == (WSDXML_NODE *)child3, "child2->Node.Next == %p\n", child2->Node.Next);
+    ok(child3->Node.Parent == parent, "child2->Node.Parent == %p\n", child2->Node.Parent);
+    ok(child3->Node.Next == NULL, "child2->Node.Next == %p\n", child2->Node.Next);
+    ok(parent->FirstChild == (WSDXML_NODE *)child1, "parent->FirstChild == %p\n", parent->FirstChild);
+
+    WSDFreeLinkedMemory(parent);
+}
+
 START_TEST(xml)
 {
     BuildAnyForSingleElement_tests();
     AddChild_tests();
+    AddSibling_tests();
 }