diff --git a/src/psbt.cpp b/src/psbt.cpp
index 28ccdcb1eaa..30c0d88a938 100644
--- a/src/psbt.cpp
+++ b/src/psbt.cpp
@@ -301,7 +301,7 @@ bool PSBTInputSigned(const PSBTInput& input)
 bool PSBTInputSignedAndVerified(const PartiallySignedTransaction psbt, unsigned int input_index, const PrecomputedTransactionData* txdata)
 {
     CTxOut utxo;
-    assert(psbt.inputs.size() >= input_index);
+    assert(input_index < psbt.inputs.size());
     const PSBTInput& input = psbt.inputs[input_index];
 
     if (input.non_witness_utxo) {