diff --git a/library/lms.c b/library/lms.c
index d3801c73f3..1c66946d75 100644
--- a/library/lms.c
+++ b/library/lms.c
@@ -506,7 +506,7 @@ static int get_merkle_path( mbedtls_lms_private_t *ctx,
 
 void mbedtls_lms_init_private( mbedtls_lms_private_t *ctx )
 {
-    mbedtls_platform_zeroize( ctx, sizeof( mbedtls_lms_public_t ) ) ;
+    mbedtls_platform_zeroize( ctx, sizeof( mbedtls_lms_private_t ) ) ;
 }
 
 void mbedtls_lms_free_private( mbedtls_lms_private_t *ctx )