diff --git a/lib/wp/client.c b/lib/wp/client.c
index 0d8a52d2..b8cfaacd 100644
--- a/lib/wp/client.c
+++ b/lib/wp/client.c
@@ -121,7 +121,7 @@ wp_client_update_permissions (WpClient * self, guint n_perm, ...)
       g_alloca (n_perm * sizeof (struct pw_permission));
 
   va_start (args, n_perm);
-  for (gint i = 0; i < n_perm; i++) {
+  for (guint i = 0; i < n_perm; i++) {
     perm[i].id = va_arg (args, guint32);
     perm[i].permissions = va_arg (args, guint32);
   }
diff --git a/lib/wp/debug.c b/lib/wp/debug.c
index d58c03f2..638dff98 100644
--- a/lib/wp/debug.c
+++ b/lib/wp/debug.c
@@ -108,7 +108,7 @@ log_level_index (GLogLevelFlags log_level)
 static inline gint
 level_index_from_spa (gint spa_lvl)
 {
-  return CLAMP (spa_lvl + 2, 0, G_N_ELEMENTS (log_level_info) - 1);
+  return CLAMP (spa_lvl + 2, 0, (gint) G_N_ELEMENTS (log_level_info) - 1);
 }
 
 static inline gint
@@ -236,7 +236,7 @@ static inline void
 extract_common_fields (struct common_fields *cf, const GLogField *fields,
     gsize n_fields)
 {
-  for (gint i = 0; i < n_fields; i++) {
+  for (guint i = 0; i < n_fields; i++) {
     if (g_strcmp0 (fields[i].key, "GLIB_DOMAIN") == 0) {
       cf->log_domain = fields[i].value;
     }
@@ -406,7 +406,7 @@ wp_log_structured_standard (
   g_log_structured_array (log_level, fields, n_fields);
 }
 
-static void
+static G_GNUC_PRINTF (6, 0) void
 wp_spa_log_logv (void *object,
     enum spa_log_level level,
     const char *file,
@@ -436,7 +436,7 @@ wp_spa_log_logv (void *object,
   g_log_structured_array (log_level, fields, SPA_N_ELEMENTS (fields));
 }
 
-static void
+static G_GNUC_PRINTF (6, 7) void
 wp_spa_log_log (void *object,
     enum spa_log_level level,
     const char *file,
diff --git a/lib/wp/endpoint.c b/lib/wp/endpoint.c
index cdf5d593..68be3334 100644
--- a/lib/wp/endpoint.c
+++ b/lib/wp/endpoint.c
@@ -760,9 +760,9 @@ impl_create_link (void *object, const struct spa_dict *props)
 
   /* convert to int - allow unspecified streams */
   self_ep_id = wp_proxy_get_bound_id (WP_PROXY (self));
-  self_stream_id = self_stream ? atoi (self_stream) : SPA_ID_INVALID;
-  peer_ep_id = atoi (peer_ep);
-  peer_stream_id = peer_stream ? atoi (peer_stream) : SPA_ID_INVALID;
+  self_stream_id = self_stream ? (guint32) atoi (self_stream) : SPA_ID_INVALID;
+  peer_ep_id = (guint32) atoi (peer_ep);
+  peer_stream_id = peer_stream ? (guint32) atoi (peer_stream) : SPA_ID_INVALID;
 
   /* find our stream */
   if (self_stream_id != SPA_ID_INVALID) {
diff --git a/lib/wp/object-interest.c b/lib/wp/object-interest.c
index 72694ae3..8e14a9ff 100644
--- a/lib/wp/object-interest.c
+++ b/lib/wp/object-interest.c
@@ -747,7 +747,7 @@ wp_object_interest_matches_full (WpObjectInterest * self,
     switch (c->type) {
       case WP_CONSTRAINT_TYPE_PW_PROPERTY:
         lookup_props = pw_props;
-        /* G_GNUC_FALLTHROUGH */;
+        SPA_FALLTHROUGH;
 
       case WP_CONSTRAINT_TYPE_PW_GLOBAL_PROPERTY: {
         const gchar *lookup_str = NULL;
diff --git a/lib/wp/object-manager.c b/lib/wp/object-manager.c
index 60289b54..2eeba620 100644
--- a/lib/wp/object-manager.c
+++ b/lib/wp/object-manager.c
@@ -552,7 +552,7 @@ static gboolean
 wp_object_manager_is_interested_in_object (WpObjectManager * self,
     GObject * object)
 {
-  gint i;
+  guint i;
   WpObjectInterest *interest = NULL;
 
   for (i = 0; i < self->interests->len; i++) {
@@ -567,7 +567,7 @@ static gboolean
 wp_object_manager_is_interested_in_global (WpObjectManager * self,
     WpGlobal * global, WpProxyFeatures * wanted_features)
 {
-  gint i;
+  guint i;
   WpObjectInterest *interest = NULL;
 
   for (i = 0; i < self->interests->len; i++) {
@@ -815,7 +815,7 @@ find_proxy_instance_type (const char * type, guint32 version)
 
   children = g_type_children (WP_TYPE_PROXY, &n_children);
 
-  for (gint i = 0; i < n_children; i++) {
+  for (guint i = 0; i < n_children; i++) {
     WpProxyClass *klass = (WpProxyClass *) g_type_class_ref (children[i]);
     if (g_strcmp0 (klass->pw_iface_type, type) == 0 &&
         klass->pw_iface_version == version) {
diff --git a/lib/wp/properties.h b/lib/wp/properties.h
index 3021c1af..f6470a80 100644
--- a/lib/wp/properties.h
+++ b/lib/wp/properties.h
@@ -131,7 +131,7 @@ gint wp_properties_setf (WpProperties * self, const gchar * key,
 
 WP_API
 gint wp_properties_setf_valist (WpProperties * self, const gchar * key,
-    const gchar * format, va_list args);
+    const gchar * format, va_list args) G_GNUC_PRINTF(3, 0);
 
 /* iterate */
 
diff --git a/modules/module-monitor.c b/modules/module-monitor.c
index fa6d740c..7e53df6f 100644
--- a/modules/module-monitor.c
+++ b/modules/module-monitor.c
@@ -666,7 +666,7 @@ wireplumber__module_init (WpModule * module, WpCore * core, GVariant * args)
       if (g_variant_lookup (value, "flags", "as", &flags_iter)) {
         const gchar *flag_str = NULL;
         while (g_variant_iter_loop (flags_iter, "&s", &flag_str)) {
-          for (gint i = 0; i < SPA_N_ELEMENTS (flag_names); i++) {
+          for (guint i = 0; i < SPA_N_ELEMENTS (flag_names); i++) {
             if (!g_strcmp0 (flag_str, flag_names[i].name))
               flags |= flag_names[i].flag;
           }
diff --git a/modules/module-si-bluez5-endpoint.c b/modules/module-si-bluez5-endpoint.c
index 1f626939..0346cbd7 100644
--- a/modules/module-si-bluez5-endpoint.c
+++ b/modules/module-si-bluez5-endpoint.c
@@ -461,11 +461,10 @@ static void
 abort_acquisition (WpSessionItem * ac, GTask *task, const gchar *msg)
 {
   g_autoptr (WpProxy) link = NULL;
-  GError *e = NULL;
 
   /* return error to abort the link activation */
-  e = g_error_new (WP_DOMAIN_LIBRARY, WP_LIBRARY_ERROR_OPERATION_FAILED, msg);
-  g_task_return_error (task, e);
+  g_task_return_new_error (task, WP_DOMAIN_LIBRARY,
+      WP_LIBRARY_ERROR_OPERATION_FAILED, "%s", msg);
 
   /* destroy the link */
   link = wp_session_item_get_associated_proxy (ac, WP_TYPE_ENDPOINT_LINK);
diff --git a/src/main.c b/src/main.c
index d3a6fd9c..bdbc84b8 100644
--- a/src/main.c
+++ b/src/main.c
@@ -40,7 +40,7 @@ struct WpDaemonData
   GPtrArray *sessions;
 };
 
-static void
+static G_GNUC_PRINTF (3, 4) void
 daemon_exit (struct WpDaemonData * d, gint code, const gchar *format, ...)
 {
   va_list args;
@@ -316,17 +316,20 @@ parse_commands_file (struct WpDaemonData *d, GInputStream * stream,
 
     /* reached the end of the data that was read */
 
-    if (cur - linestart >= sizeof (buffer)) {
+    if (cur - linestart >= (gssize) sizeof (buffer)) {
       g_set_error (error, WP_DOMAIN_DAEMON, WP_CODE_OPERATION_FAILED,
           "line %i exceeds the maximum allowed line size (%d bytes)",
           lineno, (gint) sizeof (buffer));
       return FALSE;
     } else if (cur - linestart > 0) {
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wstringop-truncation"
       /* we have unparsed data, move it to the
        * beginning of the buffer and continue */
       strncpy (buffer, linestart, cur - linestart);
       linestart = buffer;
       cur = buffer + (cur - linestart);
+#pragma GCC diagnostic pop
     } else {
       /* reset for the next g_input_stream_read() call */
       linestart = cur = buffer;
diff --git a/tests/modules/config-policy.c b/tests/modules/config-policy.c
index 9e8dbb1f..aaf08ee4 100644
--- a/tests/modules/config-policy.c
+++ b/tests/modules/config-policy.c
@@ -226,7 +226,7 @@ on_state_changed (WpEndpointLink *ep_link, WpEndpointLinkState old_state,
   case WP_ENDPOINT_LINK_STATE_ACTIVE:
     break;
   case WP_ENDPOINT_LINK_STATE_ERROR:
-    wp_message_object ("link failed: %s", error);
+    wp_warning ("link failed: %s", error);
     g_test_fail ();
   case WP_ENDPOINT_LINK_STATE_INACTIVE:
   case WP_ENDPOINT_LINK_STATE_PREPARING: