diff --git a/libguile/ports.c b/libguile/ports.c
index b97c826..f9f7a2d 100644
--- a/libguile/ports.c
+++ b/libguile/ports.c
@@ -1042,6 +1042,8 @@ scm_c_read (SCM port, void *buffer, size_t size)
 {
   scm_t_port *pt;
   size_t n_read = 0, n_available;
+  unsigned char *saved_buf;
+  size_t saved_buf_size;
 
   SCM_VALIDATE_OPINPORT (1, port);
 
@@ -1052,35 +1054,43 @@ scm_c_read (SCM port, void *buffer, size_t size)
   if (pt->rw_random)
     pt->rw_active = SCM_PORT_READ;
 
-  if (SCM_READ_BUFFER_EMPTY_P (pt))
-    {
-      if (scm_fill_input (port) == EOF)
-	return 0;
-    }
-  
-  n_available = pt->read_end - pt->read_pos;
-  
-  while (n_available < size)
+  /* Take bytes first from the port's read buffer. */
+  if (pt->read_pos < pt->read_end)
     {
+      n_available = min (size, pt->read_end - pt->read_pos);
       memcpy (buffer, pt->read_pos, n_available);
       buffer = (char *) buffer + n_available;
       pt->read_pos += n_available;
       n_read += n_available;
-      
-      if (SCM_READ_BUFFER_EMPTY_P (pt))
-	{
-	  if (scm_fill_input (port) == EOF)
-	    return n_read;
-	}
-
       size -= n_available;
-      n_available = pt->read_end - pt->read_pos;
     }
 
-  memcpy (buffer, pt->read_pos, size);
-  pt->read_pos += size;
+  /* Now we will call scm_fill_input repeatedly until we have read the
+     requested number of bytes.  (Note that a single scm_fill_input
+     call does not guarantee to fill the whole of the port's read
+     buffer.)  For these calls, since we already have a buffer here to
+     read into, we bypass the port's own read buffer (if it has one),
+     by saving it off and modifying the port structure to point to our
+     own buffer. */
+  saved_buf = pt->read_buf;
+  saved_buf_size = pt->read_buf_size;
+  pt->read_pos = pt->read_buf = pt->read_end = buffer;
+  pt->read_buf_size = size;
+
+  /* Call scm_fill_input until we have all the bytes that we need, or
+     we hit EOF. */
+  while (pt->read_buf_size && (scm_fill_input (port) != EOF))
+    {
+      pt->read_buf_size -= (pt->read_end - pt->read_pos);
+      pt->read_pos = pt->read_buf = pt->read_end;
+    }
+  n_read += pt->read_buf - (unsigned char *) buffer;
+
+  /* Reinstate the port's normal buffer. */
+  pt->read_pos = pt->read_buf = pt->read_end = saved_buf;
+  pt->read_buf_size = saved_buf_size;
 
-  return n_read + size;
+  return n_read;
 }
 #undef FUNC_NAME
 
diff --git a/libguile/srfi-4.c b/libguile/srfi-4.c
index 7d22f8b..a01f86e 100644
--- a/libguile/srfi-4.c
+++ b/libguile/srfi-4.c
@@ -886,38 +886,11 @@ SCM_DEFINE (scm_uniform_vector_read_x, "uniform-vector-read!", 1, 3, 0,
 
   if (SCM_NIMP (port_or_fd))
     {
-      scm_t_port *pt = SCM_PTAB_ENTRY (port_or_fd);
-
-      if (pt->rw_active == SCM_PORT_WRITE)
-	scm_flush (port_or_fd);
-
       ans = cend - cstart;
-      while (remaining > 0)
-	{
-	  if (pt->read_pos < pt->read_end)
-	    {
-	      size_t to_copy = min (pt->read_end - pt->read_pos,
-				    remaining);
-	      
-	      memcpy (base + off, pt->read_pos, to_copy);
-	      pt->read_pos += to_copy;
-	      remaining -= to_copy;
-	      off += to_copy;
-	    }
-	  else
-	    {
-	      if (scm_fill_input (port_or_fd) == EOF)
-		{
-		  if (remaining % sz != 0)
-		    SCM_MISC_ERROR ("unexpected EOF", SCM_EOL);
-		  ans -= remaining / sz;
-		  break;
-		}
-	    }
-	}
-      
-      if (pt->rw_random)
-	pt->rw_active = SCM_PORT_READ;
+      remaining -= scm_c_read (port_or_fd, base + off, remaining);
+      if (remaining % sz != 0)
+        SCM_MISC_ERROR ("unexpected EOF", SCM_EOL);
+      ans -= remaining / sz;
     }
   else /* file descriptor.  */
     {