diff --git a/common/flatpak-bwrap-private.h b/common/flatpak-bwrap-private.h
index 2a633d30..3c0a9941 100644
--- a/common/flatpak-bwrap-private.h
+++ b/common/flatpak-bwrap-private.h
@@ -48,7 +48,7 @@ void          flatpak_bwrap_add_noinherit_fd (FlatpakBwrap *bwrap,
 void          flatpak_bwrap_add_fd (FlatpakBwrap *bwrap,
                                     int           fd);
 void          flatpak_bwrap_add_args (FlatpakBwrap *bwrap,
-                                      ...);
+                                      ...) G_GNUC_NULL_TERMINATED;
 void          flatpak_bwrap_add_arg_printf (FlatpakBwrap *bwrap,
                                             const char   *format,
                                             ...) G_GNUC_PRINTF (2, 3);
diff --git a/icon-validator/validate-icon.c b/icon-validator/validate-icon.c
index 53dadfad..7658f128 100644
--- a/icon-validator/validate-icon.c
+++ b/icon-validator/validate-icon.c
@@ -87,6 +87,7 @@ validate_icon (const char *arg_width,
   return 0;
 }
 
+G_GNUC_NULL_TERMINATED
 static void
 add_args (GPtrArray *argv_array, ...)
 {