diff --git a/C/mavar.c b/C/mavar.c
index d50e1960c..215249250 100644
--- a/C/mavar.c
+++ b/C/mavar.c
@@ -58,10 +58,13 @@ p_setarg(void)
       Yap_Error(TYPE_ERROR_COMPOUND,ts,"setarg/3");
       return(FALSE);
     }
-    if (i < 0 || i > (Int)ArityOfFunctor(FunctorOfTerm(ts))) {
+    if (i < 1 || i > (Int)ArityOfFunctor(FunctorOfTerm(ts))) {
       if (i<0)
 	Yap_Error(DOMAIN_ERROR_NOT_LESS_THAN_ZERO,ts,"setarg/3");
       return(FALSE);
+      if (i==0)
+	Yap_Error(DOMAIN_ERROR_NOT_ZERO,ts,"setarg/3");
+      return(FALSE);
     }
     pt = RepAppl(ts)+i;
     /* the evil deed is to be done now */