diff --git a/girepository/gifunctioninfo.c b/girepository/gifunctioninfo.c
index abab97906..ca8333f9e 100644
--- a/girepository/gifunctioninfo.c
+++ b/girepository/gifunctioninfo.c
@@ -256,9 +256,9 @@ gi_invoke_error_quark (void)
 gboolean
 gi_function_info_invoke (GIFunctionInfo    *info,
                          const GIArgument  *in_args,
-                         int                n_in_args,
+                         gsize              n_in_args,
                          const GIArgument  *out_args,
-                         int                n_out_args,
+                         gsize              n_out_args,
                          GIArgument        *return_value,
                          GError           **error)
 {
diff --git a/girepository/gifunctioninfo.h b/girepository/gifunctioninfo.h
index 3f95fe680..80ec94d54 100644
--- a/girepository/gifunctioninfo.h
+++ b/girepository/gifunctioninfo.h
@@ -87,9 +87,9 @@ typedef enum
 GI_AVAILABLE_IN_ALL
 gboolean              gi_function_info_invoke         (GIFunctionInfo    *info,
                                                        const GIArgument  *in_args,
-                                                       int                n_in_args,
+                                                       gsize              n_in_args,
                                                        const GIArgument  *out_args,
-                                                       int                n_out_args,
+                                                       gsize              n_out_args,
                                                        GIArgument        *return_value,
                                                        GError           **error);