diff --git a/chardev/char-fd.c b/chardev/char-fd.c
index 2c9b2ce567..2421d8e216 100644
--- a/chardev/char-fd.c
+++ b/chardev/char-fd.c
@@ -69,13 +69,13 @@ static gboolean fd_chr_read(QIOChannel *chan, GIOCondition cond, void *opaque)
     return TRUE;
 }
 
-static int fd_chr_read_poll(void *opaque)
+static gboolean fd_chr_read_poll(void *opaque)
 {
     Chardev *chr = CHARDEV(opaque);
     FDChardev *s = FD_CHARDEV(opaque);
 
     s->max_size = qemu_chr_be_can_write(chr);
-    return s->max_size;
+    return s->max_size > 0;
 }
 
 static GSource *fd_chr_add_watch(Chardev *chr, GIOCondition cond)
diff --git a/chardev/char-io.c b/chardev/char-io.c
index 8ced184160..a264d4e7fd 100644
--- a/chardev/char-io.c
+++ b/chardev/char-io.c
@@ -30,7 +30,7 @@ typedef struct IOWatchPoll {
     QIOChannel *ioc;
     GSource *src;
 
-    IOCanReadHandler *fd_can_read;
+    GSourceFunc fd_can_read;
     GSourceFunc fd_read;
     void *opaque;
 } IOWatchPoll;
@@ -76,7 +76,7 @@ static GSourceFuncs io_watch_poll_funcs = {
 
 GSource *io_add_watch_poll(Chardev *chr,
                         QIOChannel *ioc,
-                        IOCanReadHandler *fd_can_read,
+                        GSourceFunc fd_can_read,
                         QIOChannelFunc fd_read,
                         gpointer user_data,
                         GMainContext *context)
diff --git a/chardev/char-pty.c b/chardev/char-pty.c
index e8d9a53476..626ca30cb3 100644
--- a/chardev/char-pty.c
+++ b/chardev/char-pty.c
@@ -148,13 +148,13 @@ static GSource *pty_chr_add_watch(Chardev *chr, GIOCondition cond)
     return qio_channel_create_watch(s->ioc, cond);
 }
 
-static int pty_chr_read_poll(void *opaque)
+static gboolean pty_chr_read_poll(void *opaque)
 {
     Chardev *chr = CHARDEV(opaque);
     PtyChardev *s = PTY_CHARDEV(opaque);
 
     s->read_bytes = qemu_chr_be_can_write(chr);
-    return s->read_bytes;
+    return s->read_bytes > 0;
 }
 
 static gboolean pty_chr_read(QIOChannel *chan, GIOCondition cond, void *opaque)
diff --git a/chardev/char-socket.c b/chardev/char-socket.c
index a75b46d9fe..76cc3c48b0 100644
--- a/chardev/char-socket.c
+++ b/chardev/char-socket.c
@@ -120,7 +120,7 @@ static void tcp_chr_accept(QIONetListener *listener,
                            QIOChannelSocket *cioc,
                            void *opaque);
 
-static int tcp_chr_read_poll(void *opaque);
+static gboolean tcp_chr_read_poll(void *opaque);
 static void tcp_chr_disconnect(Chardev *chr);
 
 /* Called with chr_write_lock held.  */
@@ -157,7 +157,7 @@ static int tcp_chr_write(Chardev *chr, const uint8_t *buf, int len)
     }
 }
 
-static int tcp_chr_read_poll(void *opaque)
+static gboolean tcp_chr_read_poll(void *opaque)
 {
     Chardev *chr = CHARDEV(opaque);
     SocketChardev *s = SOCKET_CHARDEV(opaque);
@@ -165,7 +165,7 @@ static int tcp_chr_read_poll(void *opaque)
         return 0;
     }
     s->max_size = qemu_chr_be_can_write(chr);
-    return s->max_size;
+    return s->max_size > 0;
 }
 
 static void tcp_chr_process_IAC_bytes(Chardev *chr,
diff --git a/chardev/char-udp.c b/chardev/char-udp.c
index 097a2f0f42..b6e399e983 100644
--- a/chardev/char-udp.c
+++ b/chardev/char-udp.c
@@ -65,7 +65,7 @@ static void udp_chr_flush_buffer(UdpChardev *s)
     }
 }
 
-static int udp_chr_read_poll(void *opaque)
+static gboolean udp_chr_read_poll(void *opaque)
 {
     Chardev *chr = CHARDEV(opaque);
     UdpChardev *s = UDP_CHARDEV(opaque);
@@ -77,7 +77,7 @@ static int udp_chr_read_poll(void *opaque)
      */
     udp_chr_flush_buffer(s);
 
-    return s->max_size;
+    return s->max_size > 0;
 }
 
 static gboolean udp_chr_read(QIOChannel *chan, GIOCondition cond, void *opaque)
diff --git a/include/chardev/char-io.h b/include/chardev/char-io.h
index 9638da5100..a173874538 100644
--- a/include/chardev/char-io.h
+++ b/include/chardev/char-io.h
@@ -31,7 +31,7 @@
 /* Can only be used for read */
 GSource *io_add_watch_poll(Chardev *chr,
                         QIOChannel *ioc,
-                        IOCanReadHandler *fd_can_read,
+                        GSourceFunc fd_can_read,
                         QIOChannelFunc fd_read,
                         gpointer user_data,
                         GMainContext *context);
