diff --git a/src/plugins/guile/weechat-guile-api.c b/src/plugins/guile/weechat-guile-api.c
index d35beba86..ebe32dbab 100644
--- a/src/plugins/guile/weechat-guile-api.c
+++ b/src/plugins/guile/weechat-guile-api.c
@@ -4974,7 +4974,9 @@ weechat_guile_api_module_init (void *data)
     port_type = scm_make_port_type ("weechat_stdout",
                                     &weechat_guile_port_fill_input,
                                     &weechat_guile_port_write);
-    guile_port = scm_c_make_port (port_type, 0, 0);
+    guile_port = scm_c_make_port (port_type, SCM_WRTNG | SCM_BUF0, 0);
+    scm_set_current_output_port (guile_port);
+    scm_set_current_error_port (guile_port);
 #else
     /* Guile < 2.2 */
     scm_t_bits port_type;
diff --git a/src/plugins/guile/weechat-guile.c b/src/plugins/guile/weechat-guile.c
index 24bedb541..ea1b3a77b 100644
--- a/src/plugins/guile/weechat-guile.c
+++ b/src/plugins/guile/weechat-guile.c
@@ -1151,11 +1151,10 @@ weechat_guile_port_fill_input (SCM port, SCM dst, size_t start, size_t count)
 {
     /* make C compiler happy */
     (void) port;
-    (void) dst;
-    (void) start;
-    (void) count;
 
-    return ' ';
+    memset (SCM_BYTEVECTOR_CONTENTS (dst) + start, ' ', count);
+
+    return count;
 }
 #else
 /* Guile < 2.2 */
@@ -1184,7 +1183,7 @@ weechat_guile_port_write (SCM port, SCM src, size_t start, size_t count)
     /* make C compiler happy */
     (void) port;
 
-    data = scm_to_locale_string (src);
+    data = SCM_BYTEVECTOR_CONTENTS (src);
 
     data2 = malloc (count + 1);
     if (!data2)