diff --git a/callback.c b/callback.c
index 3273002a..10f923d0 100644
--- a/callback.c
+++ b/callback.c
@@ -97,8 +97,10 @@ void queue_toplevel_callback(toplevel_callback_fn_t fn, void *ctx)
     cb->next = NULL;
 }
 
-void run_toplevel_callbacks(void)
+int run_toplevel_callbacks(void)
 {
+    int done_something = FALSE;
+
     if (cbhead) {
         /*
          * Transfer the head callback into cbcurr to indicate that
@@ -117,7 +119,10 @@ void run_toplevel_callbacks(void)
         cbcurr->fn(cbcurr->ctx);
         sfree(cbcurr);
         cbcurr = NULL;
+
+        done_something = TRUE;
     }
+    return done_something;
 }
 
 int toplevel_callback_pending(void)
diff --git a/putty.h b/putty.h
index a8cfcf27..7555aede 100644
--- a/putty.h
+++ b/putty.h
@@ -1595,10 +1595,15 @@ unsigned long timing_last_clock(void);
  * actually running it (e.g. so as to put a zero timeout on a select()
  * call) then it can call toplevel_callback_pending(), which will
  * return true if at least one callback is in the queue.
+ *
+ * run_toplevel_callbacks() returns TRUE if it ran any actual code.
+ * This can be used as a means of speculatively terminating a select
+ * loop, as in PSFTP, for example - if a callback has run then perhaps
+ * it might have done whatever the loop's caller was waiting for.
  */
 typedef void (*toplevel_callback_fn_t)(void *ctx);
 void queue_toplevel_callback(toplevel_callback_fn_t fn, void *ctx);
-void run_toplevel_callbacks(void);
+int run_toplevel_callbacks(void);
 int toplevel_callback_pending(void);
 void delete_callbacks_for_context(void *ctx);
 
diff --git a/unix/uxsftp.c b/unix/uxsftp.c
index 718a29c9..eb1329cf 100644
--- a/unix/uxsftp.c
+++ b/unix/uxsftp.c
@@ -459,6 +459,7 @@ static int ssh_sftp_do_select(int include_stdin, int no_fds_ok)
     int fd, fdstate, rwx, ret, maxfd;
     unsigned long now = GETTICKCOUNT();
     unsigned long next;
+    int done_something = FALSE;
 
     fdlist = NULL;
     fdcount = fdsize = 0;
@@ -509,7 +510,7 @@ static int ssh_sftp_do_select(int include_stdin, int no_fds_ok)
             tv.tv_usec = 0;
             ret = select(maxfd, &rset, &wset, &xset, &tv);
             if (ret == 0)
-                run_toplevel_callbacks();
+                done_something |= run_toplevel_callbacks();
         } else if (run_timers(now, &next)) {
             do {
                 unsigned long then;
@@ -535,7 +536,7 @@ static int ssh_sftp_do_select(int include_stdin, int no_fds_ok)
                 ret = select(maxfd, &rset, &wset, &xset, NULL);
             } while (ret < 0 && errno == EINTR);
         }
-    } while (ret == 0);
+    } while (ret == 0 && !done_something);
 
     if (ret < 0) {
 	perror("select");