diff --git a/library/pem.c b/library/pem.c
index c97e800..ed6747a 100644
--- a/library/pem.c
+++ b/library/pem.c
@@ -41,7 +41,7 @@
 #include "mbedtls/platform.h"
 #else
 #include <stdlib.h>
-#define mbedtls_malloc     malloc
+#define mbedtls_calloc    calloc
 #define mbedtls_free       free
 #endif
 
@@ -321,7 +321,7 @@
     if( ret == MBEDTLS_ERR_BASE64_INVALID_CHARACTER )
         return( MBEDTLS_ERR_PEM_INVALID_DATA + ret );
 
-    if( ( buf = mbedtls_malloc( len ) ) == NULL )
+    if( ( buf = mbedtls_calloc( 1, len ) ) == NULL )
         return( MBEDTLS_ERR_PEM_MALLOC_FAILED );
 
     if( ( ret = mbedtls_base64_decode( buf, &len, s1, s2 - s1 ) ) != 0 )
@@ -407,7 +407,7 @@
         return( MBEDTLS_ERR_BASE64_BUFFER_TOO_SMALL );
     }
 
-    if( ( encode_buf = mbedtls_malloc( use_len ) ) == NULL )
+    if( ( encode_buf = mbedtls_calloc( 1, use_len ) ) == NULL )
         return( MBEDTLS_ERR_PEM_MALLOC_FAILED );
 
     if( ( ret = mbedtls_base64_encode( encode_buf, &use_len, der_data,