diff --git a/library/x509.c b/library/x509.c
index a3e288b..3cddc5f 100644
--- a/library/x509.c
+++ b/library/x509.c
@@ -55,7 +55,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #define mbedtls_free       free
-#define mbedtls_malloc     malloc
+#define mbedtls_calloc    calloc
 #define mbedtls_printf     printf
 #define mbedtls_snprintf   snprintf
 #endif
@@ -452,7 +452,7 @@
             /* Mark this item as being no the only one in a set */
             cur->next_merged = 1;
 
-            cur->next = mbedtls_malloc( sizeof( mbedtls_x509_name ) );
+            cur->next = mbedtls_calloc( 1, sizeof( mbedtls_x509_name ) );
 
             if( cur->next == NULL )
                 return( MBEDTLS_ERR_X509_MALLOC_FAILED );
@@ -468,7 +468,7 @@
         if( *p == end )
             return( 0 );
 
-        cur->next = mbedtls_malloc( sizeof( mbedtls_x509_name ) );
+        cur->next = mbedtls_calloc( 1, sizeof( mbedtls_x509_name ) );
 
         if( cur->next == NULL )
             return( MBEDTLS_ERR_X509_MALLOC_FAILED );
@@ -597,7 +597,7 @@
     {
         mbedtls_pk_rsassa_pss_options *pss_opts;
 
-        pss_opts = mbedtls_malloc( sizeof( mbedtls_pk_rsassa_pss_options ) );
+        pss_opts = mbedtls_calloc( 1, sizeof( mbedtls_pk_rsassa_pss_options ) );
         if( pss_opts == NULL )
             return( MBEDTLS_ERR_X509_MALLOC_FAILED );