diff --git a/src/test/util/setup_common.cpp b/src/test/util/setup_common.cpp
index 62ff61b227d..cd937b2fb4b 100644
--- a/src/test/util/setup_common.cpp
+++ b/src/test/util/setup_common.cpp
@@ -41,6 +41,7 @@
 #include <streams.h>
 #include <test/util/net.h>
 #include <test/util/random.h>
+#include <test/util/transaction_utils.h>
 #include <test/util/txmempool.h>
 #include <txdb.h>
 #include <txmempool.h>
@@ -582,6 +583,9 @@ void TestChain100Setup::MockMempoolMinFee(const CFeeRate& target_feerate)
     CMutableTransaction mtx = CMutableTransaction();
     mtx.vin.emplace_back(COutPoint{Txid::FromUint256(g_insecure_rand_ctx.rand256()), 0});
     mtx.vout.emplace_back(1 * COIN, GetScriptForDestination(WitnessV0ScriptHash(CScript() << OP_TRUE)));
+    // Set a large size so that the fee evaluated at target_feerate (which is usually in sats/kvB) is an integer.
+    // Otherwise, GetMinFee() may end up slightly different from target_feerate.
+    BulkTransaction(mtx, 4000);
     const auto tx{MakeTransactionRef(mtx)};
     LockPoints lp;
     // The new mempool min feerate is equal to the removed package's feerate + incremental feerate.