diff --git a/library/pem.c b/library/pem.c
index 8dd86a4ac..a09257cc7 100644
--- a/library/pem.c
+++ b/library/pem.c
@@ -341,6 +341,7 @@ int mbedtls_pem_read_buffer( mbedtls_pem_context *ctx, const char *header, const
     ( defined(MBEDTLS_DES_C) || defined(MBEDTLS_AES_C) )
         if( pwd == NULL )
         {
+            mbedtls_zeroize( buf, len );
             mbedtls_free( buf );
             return( MBEDTLS_ERR_PEM_PASSWORD_REQUIRED );
         }
@@ -369,10 +370,12 @@ int mbedtls_pem_read_buffer( mbedtls_pem_context *ctx, const char *header, const
          */
         if( len <= 2 || buf[0] != 0x30 || buf[1] > 0x83 )
         {
+            mbedtls_zeroize( buf, len );
             mbedtls_free( buf );
             return( MBEDTLS_ERR_PEM_PASSWORD_MISMATCH );
         }
 #else
+        mbedtls_zeroize( buf, len );
         mbedtls_free( buf );
         return( MBEDTLS_ERR_PEM_FEATURE_UNAVAILABLE );
 #endif /* MBEDTLS_MD5_C && MBEDTLS_CIPHER_MODE_CBC &&