diff --git a/packages/circuits/utils/regex.circom b/packages/circuits/utils/regex.circom
index efddce28..470b1c3e 100644
--- a/packages/circuits/utils/regex.circom
+++ b/packages/circuits/utils/regex.circom
@@ -11,7 +11,7 @@ include "./bytes.circom";
 /// @param maxRevealLen Maximum length of the reveal part
 /// @input in Input array; assumes elements to be bytes
 /// @input startIndex The index from which reveal part starts; assumes a valid index, 
-///                   and `startIndex + maxRevealLen - 1` fits in `ceil(log2((maxArrayLen))` bits.
+///                   and `startIndex + maxRevealLen - 1` fits in `ceil(log2((maxArrayLen + maxRevealLen - 1))` bits.
 /// @output out Revealed data array
 template SelectRegexReveal(maxArrayLen, maxRevealLen) {
     signal input in[maxArrayLen];
@@ -19,7 +19,7 @@ template SelectRegexReveal(maxArrayLen, maxRevealLen) {
 
     signal output out[maxRevealLen];
 
-    var bitLength = log2Ceil(maxArrayLen);
+    var bitLength = log2Ceil(maxArrayLen + maxRevealLen - 1);
 
     signal isStartIndex[maxArrayLen];
     signal isZero[maxArrayLen];