diff --git a/dlls/webservices/msg.c b/dlls/webservices/msg.c
index 4a47fd358e3..01b66257dd5 100644
--- a/dlls/webservices/msg.c
+++ b/dlls/webservices/msg.c
@@ -1022,9 +1022,7 @@ HRESULT WINAPI WsAddCustomHeader( WS_MESSAGE *handle, const WS_ELEMENT_DESCRIPTI
 {
     struct msg *msg = (struct msg *)handle;
     struct header *header;
-    BOOL found = FALSE;
     HRESULT hr;
-    ULONG i;
 
     TRACE( "%p %p %08x %p %u %08x %p\n", handle, desc, option, value, size, attrs, error );
     if (error) FIXME( "ignoring error parameter\n" );
@@ -1032,30 +1030,11 @@ HRESULT WINAPI WsAddCustomHeader( WS_MESSAGE *handle, const WS_ELEMENT_DESCRIPTI
     if (!handle || !desc) return E_INVALIDARG;
     if (msg->state < WS_MESSAGE_STATE_INITIALIZED) return WS_E_INVALID_OPERATION;
 
-    for (i = 0; i < msg->header_count; i++)
-    {
-        if (msg->header[i]->type || msg->header[i]->mapped) continue;
-        if (WsXmlStringEquals( desc->elementLocalName, &msg->header[i]->name, NULL ) &&
-            WsXmlStringEquals( desc->elementNs, &msg->header[i]->ns, NULL ) == S_OK)
-        {
-            found = TRUE;
-            break;
-        }
-    }
-
-    if (!found)
-    {
-        if ((hr = grow_header_array( msg, msg->header_count + 1 )) != S_OK) return hr;
-        i = msg->header_count;
-    }
-
+    if ((hr = grow_header_array( msg, msg->header_count + 1 )) != S_OK) return hr;
     if ((hr = build_custom_header( msg->heap, desc->elementLocalName, desc->elementNs, desc->type,
                                    desc->typeDescription, option, value, size, &header )) != S_OK) return hr;
 
-    if (!found) msg->header_count++;
-    else free_header( msg->header[i] );
-
-    msg->header[i] = header;
+    msg->header[msg->header_count++] = header;
     return write_envelope( msg );
 }
 
diff --git a/dlls/webservices/tests/msg.c b/dlls/webservices/tests/msg.c
index 0a8456add7c..b78c52ea1ba 100644
--- a/dlls/webservices/tests/msg.c
+++ b/dlls/webservices/tests/msg.c
@@ -749,8 +749,22 @@ static void test_WsAddCustomHeader(void)
         "xmlns:s=\"http://www.w3.org/2003/05/soap-envelope\"><s:Header>"
         "<a:MessageID>urn:uuid:00000000-0000-0000-0000-000000000000</a:MessageID>"
         "</s:Header><s:Body/></s:Envelope>";
+    static const char expected3[] =
+        "<s:Envelope xmlns:a=\"http://www.w3.org/2005/08/addressing\" "
+        "xmlns:s=\"http://www.w3.org/2003/05/soap-envelope\"><s:Header>"
+        "<a:MessageID>urn:uuid:00000000-0000-0000-0000-000000000000</a:MessageID>"
+        "<header xmlns=\"ns\">value</header><header xmlns=\"ns\">value2</header>"
+        "</s:Header><s:Body/></s:Envelope>";
+    static const char expected4[] =
+        "<s:Envelope xmlns:a=\"http://www.w3.org/2005/08/addressing\" "
+        "xmlns:s=\"http://www.w3.org/2003/05/soap-envelope\"><s:Header>"
+        "<a:MessageID>urn:uuid:00000000-0000-0000-0000-000000000000</a:MessageID>"
+        "<header xmlns=\"ns\">value</header><header xmlns=\"ns\">value2</header>"
+        "<header2 xmlns=\"ns\">value2</header2></s:Header><s:Body/></s:Envelope>";
     static WS_XML_STRING header = {6, (BYTE *)"header"}, ns = {2, (BYTE *)"ns"};
+    static WS_XML_STRING header2 = {7, (BYTE *)"header2"};
     static WCHAR valueW[] = {'v','a','l','u','e',0};
+    static WCHAR value2W[] = {'v','a','l','u','e','2',0};
     HRESULT hr;
     WS_MESSAGE *msg;
     WS_ELEMENT_DESCRIPTION desc;
@@ -797,6 +811,16 @@ static void test_WsAddCustomHeader(void)
     ok( hr == S_OK, "got %08x\n", hr );
     check_output_header( msg, expected, -1, strstr(expected, "urn:uuid:") - expected, 46, __LINE__ );
 
+    test.value = value2W;
+    hr = WsAddCustomHeader( msg, &desc, WS_WRITE_REQUIRED_VALUE, &test, sizeof(test), 0, NULL );
+    ok( hr == S_OK, "got %08x\n", hr );
+    check_output_header( msg, expected3, -1, strstr(expected3, "urn:uuid:") - expected3, 46, __LINE__ );
+
+    desc.elementLocalName = &header2;
+    hr = WsAddCustomHeader( msg, &desc, WS_WRITE_REQUIRED_VALUE, &test, sizeof(test), 0, NULL );
+    ok( hr == S_OK, "got %08x\n", hr );
+    check_output_header( msg, expected4, -1, strstr(expected4, "urn:uuid:") - expected4, 46, __LINE__ );
+
     hr = WsAddCustomHeader( msg, &desc, WS_WRITE_REQUIRED_VALUE, NULL, 0, 0, NULL );
     ok( hr == E_INVALIDARG, "got %08x\n", hr );