diff --git a/include/mbedtls/bignum.h b/include/mbedtls/bignum.h
index d706a2c..788ea21 100644
--- a/include/mbedtls/bignum.h
+++ b/include/mbedtls/bignum.h
@@ -66,7 +66,7 @@
 
 #if !defined(MBEDTLS_MPI_WINDOW_SIZE)
 /*
- * Maximum window size used for modular exponentiation. Default: 6
+ * Maximum window size used for modular exponentiation. Default: 2
  * Minimum value: 1. Maximum value: 6.
  *
  * Result is an array of ( 2 ** MBEDTLS_MPI_WINDOW_SIZE ) MPIs used
@@ -74,7 +74,7 @@
  *
  * Reduction in size, reduces speed.
  */
-#define MBEDTLS_MPI_WINDOW_SIZE                           6        /**< Maximum window size used. */
+#define MBEDTLS_MPI_WINDOW_SIZE                           2        /**< Maximum window size used. */
 #endif /* !MBEDTLS_MPI_WINDOW_SIZE */
 
 #if !defined(MBEDTLS_MPI_MAX_SIZE)