diff --git a/impurity/check_for_impurity.se b/impurity/check_for_impurity.se
index e4ccae0..856c6ee 100644
--- a/impurity/check_for_impurity.se
+++ b/impurity/check_for_impurity.se
@@ -57,5 +57,5 @@ def submit(addr: address):
     self.approved_addrs[addr] = 1
     return(1: bool)
 
-def check(addr: address):
+def const check(addr: address):
     return(self.approved_addrs[addr]:bool)
diff --git a/impurity/impurity_tester.py b/impurity/impurity_tester.py
index e1db22b..f73b90e 100644
--- a/impurity/impurity_tester.py
+++ b/impurity/impurity_tester.py
@@ -120,3 +120,4 @@ print('Send %d wei to %s' % (t.startgas * t.gasprice,
 
 print('Contract address: 0x'+utils.encode_hex(utils.mk_contract_address(t.sender, 0)))
 print('Code: 0x'+utils.encode_hex(rlp.encode(t)))
+print('ABI declaration: '+repr(serpent.mk_full_signature('check_for_impurity.se')))