diff --git a/glx/indirect_util.c b/glx/indirect_util.c
index 3798731b8..daa820edd 100644
--- a/glx/indirect_util.c
+++ b/glx/indirect_util.c
@@ -131,13 +131,10 @@ __glXSendReply(ClientPtr client, const void *data, size_t elements,
         .retval = retval,
     };
 
-    /* It is faster on almost always every architecture to just copy the 8
-     * bytes, even when not necessary, than check to see of the value of
-     * elements requires it.  Copying the data when not needed will do no
-     * harm.
-     */
-
-    (void) memcpy(&reply.pad3, data, 8);
+    /* Single element goes in reply padding; don't leak uninitialized data. */
+    if (elements == 1) {
+        (void) memcpy(&reply.pad3, data, element_size);
+    }
     WriteToClient(client, sz_xGLXSingleReply, &reply);
 
     if (reply_ints != 0) {
@@ -179,13 +176,10 @@ __glXSendReplySwap(ClientPtr client, const void *data, size_t elements,
         .retval = bswap_32(retval),
     };
 
-    /* It is faster on almost always every architecture to just copy the 8
-     * bytes, even when not necessary, than check to see of the value of
-     * elements requires it.  Copying the data when not needed will do no
-     * harm.
-     */
-
-    (void) memcpy(&reply.pad3, data, 8);
+    /* Single element goes in reply padding; don't leak uninitialized data. */
+    if (elements == 1) {
+        (void) memcpy(&reply.pad3, data, element_size);
+    }
     WriteToClient(client, sz_xGLXSingleReply, &reply);
 
     if (reply_ints != 0) {