diff --git a/library/bignum.c b/library/bignum.c
index 0a0022c..61353ca 100644
--- a/library/bignum.c
+++ b/library/bignum.c
@@ -72,7 +72,7 @@
     }
 
     /*
-     * Set sign_N to 1 if N >= 0, 0 if N < 0.
+     * Set N_is_negative to MBEDTLS_CT_FALSE if N >= 0, MBEDTLS_CT_TRUE if N < 0.
      * We know that N->s == 1 if N >= 0 and N->s == -1 if N < 0.
      */
     X_is_negative = mbedtls_ct_bool((X->s & 2) >> 1);
@@ -83,7 +83,7 @@
      * That is if X is negative (X_is_negative == 1), then X < Y is true and it
      * is false if X is positive (X_is_negative == 0).
      */
-    different_sign = mbedtls_ct_bool_xor(X_is_negative, Y_is_negative); // non-zero if different sign
+    different_sign = mbedtls_ct_bool_xor(X_is_negative, Y_is_negative); // true if different sign
     result = mbedtls_ct_bool_and(different_sign, X_is_negative);
 
     /*