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)
diff --git a/include/mbedtls/config.h b/include/mbedtls/config.h
index 5dcbdd1..1e4d95e 100644
--- a/include/mbedtls/config.h
+++ b/include/mbedtls/config.h
@@ -3749,7 +3749,7 @@
  * comment in the specific module. */
 
 /* MPI / BIGNUM options */
-//#define MBEDTLS_MPI_WINDOW_SIZE            6 /**< Maximum window size used. */
+//#define MBEDTLS_MPI_WINDOW_SIZE            2 /**< Maximum window size used. */
 //#define MBEDTLS_MPI_MAX_SIZE            1024 /**< Maximum number of bytes for usable MPIs. */
 
 /* CTR_DRBG options */