diff --git a/src/xcl/xcblock.c b/src/xcl/xcblock.c
index 56decd65..ee48608c 100644
--- a/src/xcl/xcblock.c
+++ b/src/xcl/xcblock.c
@@ -155,8 +155,7 @@ static inline int issue_complete_request(Display *dpy, int veclen, struct iovec
     unsigned int sequence;
     int flags = XCB_REQUEST_RAW;
     int i;
-    CARD32 len;
-    size_t rem;
+    size_t len;
 
     /* skip empty iovecs. if no iovecs remain, we're done. */
     while(veclen > 0 && vec[0].iov_len == 0)
@@ -171,13 +170,14 @@ static inline int issue_complete_request(Display *dpy, int veclen, struct iovec
     if(len == 0)
 	/* it's a bigrequest. dig out the *real* length field. */
 	len = ((CARD32 *) vec[0].iov_base)[1];
+    len <<= 2;
 
     /* do we have enough data for a complete request? how many iovec
      * elements does it span? */
     for(i = 0; i < veclen; ++i)
     {
-	CARD32 oldlen = len;
-	len -= (vec[i].iov_len + 3) >> 2;
+	size_t oldlen = len;
+	len -= vec[i].iov_len;
 	/* if len is now 0 or has wrapped, we have enough data. */
 	if((len - 1) > oldlen)
 	    break;
@@ -188,16 +188,9 @@ static inline int issue_complete_request(Display *dpy, int veclen, struct iovec
     /* we have enough data to issue one complete request. the remaining
      * code can't fail. */
 
-    /* len says how far we overshot our data needs in 4-byte units.
-     * (it's negative if we actually overshot, or 0 if we're right on.)
-     * rem is overshoot in 1-byte units, so it needs to have trailing
-     * padding subtracted off if we're not using that padding in this
-     * request. */
-    if(len)
-	rem = (-len << 2) - (-vec[i].iov_len & 3);
-    else
-	rem = 0;
-    vec[i].iov_len -= rem;
+    /* len says how far we overshot our data needs. (it's "negative" if
+     * we actually overshot, or 0 if we're right on.) */
+    vec[i].iov_len += len;
     xcb_req.count = i + 1;
     xcb_req.opcode = ((CARD8 *) vec[0].iov_base)[0];
 
@@ -211,7 +204,7 @@ static inline int issue_complete_request(Display *dpy, int veclen, struct iovec
 
     /* update the iovecs to refer only to data not yet sent. */
     vec[i].iov_base = (char *) vec[i].iov_base + vec[i].iov_len;
-    vec[i].iov_len = rem;
+    vec[i].iov_len = -len;
     while(--i >= 0)
 	vec[i].iov_len = 0;
 
@@ -233,9 +226,11 @@ static inline int issue_complete_request(Display *dpy, int veclen, struct iovec
 
 void _XPutXCBBuffer(Display *dpy)
 {
+    static char const pad[3];
+    const int padsize = -dpy->xcl->request_extra_size & 3;
     XCBConnection *c = dpy->xcl->connection;
     _XExtension *ext;
-    struct iovec iov[2];
+    struct iovec iov[5];
 
     assert_sequence_less(dpy->last_request_read, dpy->request);
     assert_sequence_less(XCBGetRequestSent(c), dpy->request);
@@ -245,8 +240,6 @@ void _XPutXCBBuffer(Display *dpy)
 	ext->before_flush(dpy, &ext->codes, dpy->buffer, dpy->bufptr - dpy->buffer);
 	if(dpy->xcl->request_extra)
 	{
-	    static char const pad[3];
-	    int padsize = -dpy->xcl->request_extra_size & 3;
 	    ext->before_flush(dpy, &ext->codes, dpy->xcl->request_extra, dpy->xcl->request_extra_size);
 	    if(padsize)
 		ext->before_flush(dpy, &ext->codes, pad, padsize);
@@ -257,11 +250,13 @@ void _XPutXCBBuffer(Display *dpy)
     iov[0].iov_len = dpy->bufptr - dpy->buffer;
     iov[1].iov_base = (caddr_t) dpy->xcl->request_extra;
     iov[1].iov_len = dpy->xcl->request_extra_size;
+    iov[2].iov_base = (caddr_t) pad;
+    iov[2].iov_len = padsize;
 
-    while(issue_complete_request(dpy, 2, iov))
+    while(issue_complete_request(dpy, 3, iov))
 	/* empty */;
 
-    assert(iov[0].iov_len == 0 && iov[1].iov_len == 0);
+    assert(iov[0].iov_len == 0 && iov[1].iov_len == 0 && iov[2].iov_len == 0);
 
     dpy->xcl->request_extra = 0;
     dpy->xcl->request_extra_size = 0;