diff --git a/library/bignum.c b/library/bignum.c
index f06eff0..11acc01 100644
--- a/library/bignum.c
+++ b/library/bignum.c
@@ -2278,7 +2278,7 @@
          * TA-TB is even so the division by 2 has an integer result.
          * Invariant (I) is preserved since any odd divisor of both TA and TB
          * also divides |TA-TB|/2, and any odd divisor of both TA and |TA-TB|/2
-         * also divides TB, and any odd divisior of both TB and |TA-TB|/2 also
+         * also divides TB, and any odd divisor of both TB and |TA-TB|/2 also
          * divides TA.
          */
         if( mbedtls_mpi_cmp_mpi( &TA, &TB ) >= 0 )