diff --git a/src/drv_imap.c b/src/drv_imap.c
index 6a1394d..31fdf28 100644
--- a/src/drv_imap.c
+++ b/src/drv_imap.c
@@ -335,7 +335,7 @@ cmd_submittable( imap_store_t *ctx, struct imap_cmd *cmd )
 	       ctx->num_in_progress < ((imap_store_conf_t *)ctx->gen.conf)->server->max_in_progress;
 }
 
-static int
+static void
 flush_imap_cmds( imap_store_t *ctx )
 {
 	struct imap_cmd *cmd;
@@ -345,7 +345,6 @@ flush_imap_cmds( imap_store_t *ctx )
 			ctx->pending_append = &ctx->pending;
 		send_imap_cmd( ctx, cmd );
 	}
-	return 0;
 }
 
 static void
@@ -1589,7 +1588,7 @@ imap_open_store( store_conf_t *conf, const char *label,
 
 	socket_init( &ctx->conn, &srvc->sconf,
 	             (void (*)( void * ))imap_invoke_bad_callback,
-	             imap_socket_read, (int (*)(void *))flush_imap_cmds, ctx );
+	             imap_socket_read, (void (*)(void *))flush_imap_cmds, ctx );
 	socket_connect( &ctx->conn, imap_open_store_connected );
 }
 
diff --git a/src/socket.c b/src/socket.c
index 8a3b33b..5c1ce93 100644
--- a/src/socket.c
+++ b/src/socket.c
@@ -80,7 +80,7 @@ ssl_return( const char *func, conn_t *conn, int ret )
 				/* Callers take the short path out, so signal higher layers from here. */
 				conn->state = SCK_EOF;
 				conn->read_callback( conn->callback_aux );
-				return 0;
+				return -1;
 			}
 			sys_error( "Socket error: secure %s %s", func, conn->name );
 		} else {
@@ -766,7 +766,8 @@ do_queued_write( conn_t *conn )
 		conf_wakeup( &conn->ssl_fake, 0 );
 #endif
 	conn->writing = 0;
-	return conn->write_callback( conn->callback_aux );
+	conn->write_callback( conn->callback_aux );
+	return -1;
 }
 
 static void
diff --git a/src/socket.h b/src/socket.h
index dac2576..84ae0a2 100644
--- a/src/socket.h
+++ b/src/socket.h
@@ -88,7 +88,7 @@ typedef struct {
 
 	void (*bad_callback)( void *aux ); /* async fail while sending or listening */
 	void (*read_callback)( void *aux ); /* data available for reading */
-	int (*write_callback)( void *aux ); /* all *queued* data was sent */
+	void (*write_callback)( void *aux ); /* all *queued* data was sent */
 	union {
 		void (*connect)( int ok, void *aux );
 		void (*starttls)( int ok, void *aux );
@@ -123,7 +123,7 @@ static INLINE void socket_init( conn_t *conn,
                                 const server_conf_t *conf,
                                 void (*bad_callback)( void *aux ),
                                 void (*read_callback)( void *aux ),
-                                int (*write_callback)( void *aux ),
+                                void (*write_callback)( void *aux ),
                                 void *aux )
 {
 	conn->conf = conf;