diff --git a/src/polkitbackend/polkitbackendauthority.c b/src/polkitbackend/polkitbackendauthority.c
index 86ca632f..0c09f7b0 100644
--- a/src/polkitbackend/polkitbackendauthority.c
+++ b/src/polkitbackend/polkitbackendauthority.c
@@ -1697,6 +1697,7 @@ _color_get (_Color color)
 
 /* ---------------------------------------------------------------------------------------------------- */
 
+G_GNUC_PRINTF(3, 4)
 void
 polkit_backend_authority_log (PolkitBackendAuthority *authority,
                               const guint message_log_level,
diff --git a/src/programs/pkexec.c b/src/programs/pkexec.c
index 61c91003..38b7f7e7 100644
--- a/src/programs/pkexec.c
+++ b/src/programs/pkexec.c
@@ -86,6 +86,7 @@ usage (int argc, char *argv[])
 
 /* ---------------------------------------------------------------------------------------------------- */
 
+G_GNUC_PRINTF(3, 4)
 static void
 log_message (gint     level,
              gboolean print_to_stderr,