diff --git a/library/md5.c b/library/md5.c
index 009a013..9c75cae 100644
--- a/library/md5.c
+++ b/library/md5.c
@@ -266,6 +266,13 @@
     ctx->state[2] += C;
     ctx->state[3] += D;
 
+    /* Zeroise variables to clear sensitive data from memory. */
+    mbedtls_zeroize( &X, sizeof( X ) );
+    mbedtls_zeroize( &A, sizeof( A ) );
+    mbedtls_zeroize( &B, sizeof( B ) );
+    mbedtls_zeroize( &C, sizeof( C ) );
+    mbedtls_zeroize( &D, sizeof( D ) );
+
     return( 0 );
 }