diff --git a/src.ts/contract.ts b/src.ts/contract.ts
index ca8eabce..2744cde2 100644
--- a/src.ts/contract.ts
+++ b/src.ts/contract.ts
@@ -158,9 +158,10 @@ function runMethod(contract: Contract, functionName: string, estimateOnly: boole
 
             if (tx.blockTag != null) {
                 blockTag = tx.blockTag;
-                delete tx.blockTag;
             }
 
+            delete tx.blockTag;
+
             // Check for unexpected keys (e.g. using "gas" instead of "gasLimit")
             for (let key in tx) {
                 if (!allowedTransactionKeys[key]) {