diff --git a/src/if_perl.xs b/src/if_perl.xs
index e1e6ada..9b8d2c2 100644
--- a/src/if_perl.xs
+++ b/src/if_perl.xs
@@ -611,7 +611,7 @@
     if (ptr->w_perl_private == NULL)
     {
 	ptr->w_perl_private = newSV(0);
-	sv_setiv(ptr->w_perl_private, (IV)ptr);
+	sv_setiv(ptr->w_perl_private, PTR2IV(ptr));
     }
     else
 	SvREFCNT_inc(ptr->w_perl_private);
@@ -629,7 +629,7 @@
     if (ptr->b_perl_private == NULL)
     {
 	ptr->b_perl_private = newSV(0);
-	sv_setiv(ptr->b_perl_private, (IV)ptr);
+	sv_setiv(ptr->b_perl_private, PTR2IV(ptr));
     }
     else
 	SvREFCNT_inc(ptr->b_perl_private);