diff --git a/glib/garray.c b/glib/garray.c
index 413ea8539..f67099315 100644
--- a/glib/garray.c
+++ b/glib/garray.c
@@ -2338,23 +2338,23 @@ g_ptr_array_insert (GPtrArray *array,
                     gpointer   data)
 {
   GRealPtrArray *rarray = (GRealPtrArray *)array;
+  guint real_index;
 
   g_return_if_fail (rarray);
   g_return_if_fail (index_ >= -1);
-  g_return_if_fail (index_ <= (gint)rarray->len);
+  g_return_if_fail (index_ < 0 || (guint) index_ <= rarray->len);
 
   g_ptr_array_maybe_expand (rarray, 1u + rarray->null_terminated);
 
-  if (index_ < 0)
-    index_ = rarray->len;
+  real_index = (index_ >= 0) ? (guint) index_ : rarray->len;
 
-  if ((guint) index_ < rarray->len)
-    memmove (&(rarray->pdata[index_ + 1]),
-             &(rarray->pdata[index_]),
-             (rarray->len - index_) * sizeof (gpointer));
+  if (real_index < rarray->len)
+    memmove (&(rarray->pdata[real_index + 1]),
+             &(rarray->pdata[real_index]),
+             (rarray->len - real_index) * sizeof (gpointer));
 
   rarray->len++;
-  rarray->pdata[index_] = data;
+  rarray->pdata[real_index] = data;
 
   ptr_array_maybe_null_terminate (rarray);
 }