diff --git a/library/pk.c b/library/pk.c
index d46a934..dcdfd1a 100644
--- a/library/pk.c
+++ b/library/pk.c
@@ -672,6 +672,8 @@
         return MBEDTLS_ERR_PK_HW_ACCEL_FAILED;
     }
 
+    mbedtls_platform_zeroize(d, sizeof(d));
+
     /* make PK context wrap the key slot */
     mbedtls_pk_free(pk);
     mbedtls_pk_init(pk);