1 files changed, 10 insertions, 5 deletions

diff --git a/builtins.c b/builtins.c
index 8215930..7c20b17 100644
--- a/builtins.c
+++ b/builtins.c
@@ -372,18 +372,23 @@ builtinarg(Term *goal, Binding **bindings, Module *module)
 	Term *term = n->next;
 	Term *arg = term->next;
 
+	if(n->tag == VariableTerm || term->tag == VariableTerm)
+		Throw(instantiationerror());
 	if(n->tag != IntegerTerm)
-		return 0;
+		Throw(typeerror(L"integer", n));
+	if(term->tag != CompoundTerm)
+		Throw(typeerror(L"compound", term));
 	if(n->ival < 0)
 		Throw(domainerror(L"not_less_than_zero", n));
-	if(term->tag != CompoundTerm)
-		return 0;
-	if(n->ival >= term->arity)
+
+	if(n->ival > term->arity)
 		return 0;
 
+	print("Passed checks!\n");
+
 	int i;
 	Term *t;
-	for(i = 0, t = term->children; i < n->ival; i++, t = t->next);
+	for(i = 1, t = term->children; i < n->ival; i++, t = t->next);
 	return unify(arg, t, bindings);
 }