diff --git a/src/denomination.ml b/src/denomination.ml
index 710f8921..bf6f63a7 100644
--- a/src/denomination.ml
+++ b/src/denomination.ml
@@ -16,6 +16,23 @@ type t = {
   master_sig: Signatures.DenominationKeyValidity.t;
 }
 
+let verify_denomination_key_validity ~key ~signature dn =
+  let open Signatures.DenominationKeyValidity in
+  verify key signature
+    {
+      R.master= key;
+      start= dn.stamp_start;
+      expire_withdraw= dn.stamp_expire_withdraw;
+      expire_spend= dn.stamp_expire_deposit;
+      expire_legal= dn.stamp_expire_legal;
+      value= dn.value;
+      fee_withdraw= dn.fee_withdraw;
+      fee_deposit= dn.fee_deposit;
+      fee_refresh= dn.fee_refresh;
+      fee_refund= dn.fee_refund;
+      denom_hash= dn.h_pub;
+    }
+
 let make_denom_group_sorted denominations =
   let open Syntax in
   (* use hashtbl to re-group denoms *)
diff --git a/src/verify_signature.ml b/src/verify_signature.ml
deleted file mode 100644
index feee28fe..00000000
--- a/src/verify_signature.ml
+++ /dev/null
@@ -1,17 +0,0 @@
-let denomination_key_validity ~key dn =
-  let open Denomination in
-  let open Signatures.DenominationKeyValidity in
-  verify key dn.master_sig
-    {
-      R.master= key;
-      start= dn.stamp_start;
-      expire_withdraw= dn.stamp_expire_withdraw;
-      expire_spend= dn.stamp_expire_deposit;
-      expire_legal= dn.stamp_expire_legal;
-      value= dn.value;
-      fee_withdraw= dn.fee_withdraw;
-      fee_deposit= dn.fee_deposit;
-      fee_refresh= dn.fee_refresh;
-      fee_refund= dn.fee_refund;
-      denom_hash= dn.h_pub;
-    }