diff --git a/lnpbp-0020.md b/lnpbp-0020.md
index b1b7479..9174491 100644
--- a/lnpbp-0020.md
+++ b/lnpbp-0020.md
@@ -82,7 +82,7 @@ interface RGB20
     global created :: RGBTypes.Timestamp
 
     -- State which accumulates amounts issued
-    global issuedSupply* :: Amount
+    global issuedSupply+ :: Amount
     -- State which accumulates amounts burned
     global burnedSupply* :: Amount
     -- State which accumulates amounts burned and then replaced