diff --git a/es/tx/builder/helpers.js b/es/tx/builder/helpers.js
index ca4e99b5c6..d0624185af 100644
--- a/es/tx/builder/helpers.js
+++ b/es/tx/builder/helpers.js
@@ -297,11 +297,11 @@ export function computeBidFee (domain, startFee = NAME_FEE, increment = NAME_FEE
 
 export function computeAuctionEndBlock (domain, claimHeight) {
   return R.cond([
-    [R.lt(5), R.always(NAME_BID_TIMEOUTS[4] + claimHeight)],
-    [R.lt(9), R.always(NAME_BID_TIMEOUTS[8] + claimHeight)],
-    [R.lte(NAME_BID_MAX_LENGTH), R.always(NAME_BID_TIMEOUTS[12] + claimHeight)],
-    [R.T, R.always(claimHeight)]
-  ])(domain.replace('.chain', '').length)
+    [R.lt(5), R.always(NAME_BID_TIMEOUTS[4].plus(claimHeight))],
+    [R.lt(9), R.always(NAME_BID_TIMEOUTS[8].plus(claimHeight))],
+    [R.lte(NAME_BID_MAX_LENGTH), R.always(NAME_BID_TIMEOUTS[12].plus(claimHeight))],
+    [R.T, R.always(BigNumber(claimHeight))]
+  ])(domain.replace('.chain', '').length).toString(10)
 }
 
 export default {
diff --git a/es/tx/builder/schema.js b/es/tx/builder/schema.js
index c730e6b902..af0f024b0d 100644
--- a/es/tx/builder/schema.js
+++ b/es/tx/builder/schema.js
@@ -70,10 +70,10 @@ export const NAME_BID_RANGES = {
 // # ref: https://github.com/aeternity/aeternity/blob/72e440b8731422e335f879a31ecbbee7ac23a1cf/apps/aecore/src/aec_governance.erl#L273
 // # name bid timeouts
 export const NAME_BID_TIMEOUTS = {
-  13: 0,
-  12: NAME_BID_TIMEOUT_BLOCKS, // # 480 blocks
-  8: 31 * NAME_BID_TIMEOUT_BLOCKS, // # 14880 blocks
-  4: 62 * NAME_BID_TIMEOUT_BLOCKS // # 29760 blocks
+  13: BigNumber(0),
+  12: BigNumber(NAME_BID_TIMEOUT_BLOCKS), // # 480 blocks
+  8: BigNumber(31).times(NAME_BID_TIMEOUT_BLOCKS), // # 14880 blocks
+  4: BigNumber(62).times(NAME_BID_TIMEOUT_BLOCKS) // # 29760 blocks
 }
 
 // # Tag constant for ids (type uint8)