diff --git a/glx/vndcmds.c b/glx/vndcmds.c
index f0779d14a26161abef41a6fc782a077ee60d2051..21c6fef9ea57e7e4f40d182e1ea2881fce18aacd 100644
--- a/glx/vndcmds.c
+++ b/glx/vndcmds.c
@@ -468,15 +468,24 @@ void GlxDispatchReset(void)
 int GlxDispatchRequest(ClientPtr client)
 {
     REQUEST(xReq);
+    int result;
+
     if (GlxExtensionEntry->base == 0)
         return BadRequest;
+
+    GlxSetRequestClient(client);
+
     if (stuff->data < OPCODE_ARRAY_LEN) {
         if (dispatchFuncs[stuff->data] == NULL) {
             // Try to find a dispatch stub.
             dispatchFuncs[stuff->data] = GetVendorDispatchFunc(stuff->data, 0);
         }
-        return dispatchFuncs[stuff->data](client);
+        result = dispatchFuncs[stuff->data](client);
     } else {
-        return dispatch_GLXSingle(client);
+        result = dispatch_GLXSingle(client);
     }
+
+    GlxSetRequestClient(NULL);
+
+    return result;
 }
diff --git a/glx/vndserver.h b/glx/vndserver.h
index 78246d212cea42f923808852159c973e3b64318d..613fef0fe221b5a1fbc8d35b562edb167b772196 100644
--- a/glx/vndserver.h
+++ b/glx/vndserver.h
@@ -95,6 +95,13 @@ Bool GlxAddXIDMap(XID id, GlxServerVendor *vendor);
 GlxServerVendor * GlxGetXIDMap(XID id);
 void GlxRemoveXIDMap(XID id);
 
+/**
+ * Records the client that sent the current request. This is needed in
+ * GlxGetXIDMap to know which client's (screen -> vendor) mapping to use for a
+ * regular X window.
+ */
+void GlxSetRequestClient(ClientPtr client);
+
 GlxContextTagInfo *GlxAllocContextTag(ClientPtr client, GlxServerVendor *vendor);
 GlxContextTagInfo *GlxLookupContextTag(ClientPtr client, GLXContextTag tag);
 void GlxFreeContextTag(GlxContextTagInfo *tagInfo);
diff --git a/glx/vndservermapping.c b/glx/vndservermapping.c
index 778656bb6eadcad43afe0e985c14a67eb44402a4..4efab8b81d1eadd84ada3de078e17d7ad51661d6 100644
--- a/glx/vndservermapping.c
+++ b/glx/vndservermapping.c
@@ -33,6 +33,13 @@
 
 #include "vndservervendor.h"
 
+static ClientPtr requestClient = NULL;
+
+void GlxSetRequestClient(ClientPtr client)
+{
+    requestClient = client;
+}
+
 static GlxServerVendor *LookupXIDMapResource(XID id)
 {
     void *ptr = NULL;
@@ -59,10 +66,7 @@ GlxServerVendor *GlxGetXIDMap(XID id)
                                          DixGetAttrAccess);
         if (rv == Success && ptr != NULL) {
             DrawablePtr draw = (DrawablePtr) ptr;
-            GlxScreenPriv *screenPriv = GlxGetScreen(draw->pScreen);
-            if (screenPriv != NULL) {
-                vendor = screenPriv->vendor;
-            }
+            vendor = GlxGetVendorForScreen(requestClient, draw->pScreen);
         }
     }
     return vendor;