diff --git a/include/polarssl/bignum.h b/include/polarssl/bignum.h
index f832db5..ecc4a13 100644
--- a/include/polarssl/bignum.h
+++ b/include/polarssl/bignum.h
@@ -134,7 +134,7 @@
 #else
   /*
    * 32-bit integers can be forced on 64-bit arches (eg. for testing purposes)
-   * by defining POLARSSL_HAVE_INT32 and undefining POARSSL_HAVE_ASM
+   * by defining POLARSSL_HAVE_INT32 and undefining POLARSSL_HAVE_ASM
    */
   #if ( ! defined(POLARSSL_HAVE_INT32) && \
           defined(_MSC_VER) && defined(_M_AMD64) )