diff --git a/library/bignum.c b/library/bignum.c
index 9776092..b65858d 100644
--- a/library/bignum.c
+++ b/library/bignum.c
@@ -46,7 +46,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #define mbedtls_printf     printf
-#define mbedtls_malloc     malloc
+#define mbedtls_calloc    calloc
 #define mbedtls_free       free
 #endif
 
@@ -109,11 +109,9 @@
 
     if( X->n < nblimbs )
     {
-        if( ( p = mbedtls_malloc( nblimbs * ciL ) ) == NULL )
+        if( ( p = mbedtls_calloc( nblimbs, ciL ) ) == NULL )
             return( MBEDTLS_ERR_MPI_MALLOC_FAILED );
 
-        memset( p, 0, nblimbs * ciL );
-
         if( X->p != NULL )
         {
             memcpy( p, X->p, X->n * ciL );
@@ -149,11 +147,9 @@
     if( i < nblimbs )
         i = nblimbs;
 
-    if( ( p = mbedtls_malloc( i * ciL ) ) == NULL )
+    if( ( p = mbedtls_calloc( i, ciL ) ) == NULL )
         return( MBEDTLS_ERR_MPI_MALLOC_FAILED );
 
-    memset( p, 0, i * ciL );
-
     if( X->p != NULL )
     {
         memcpy( p, X->p, i * ciL );