diff --git a/regress/misc/sk-dummy/sk-dummy.c b/regress/misc/sk-dummy/sk-dummy.c
index db4946acb..d2b3ed43e 100644
--- a/regress/misc/sk-dummy/sk-dummy.c
+++ b/regress/misc/sk-dummy/sk-dummy.c
@@ -356,7 +356,7 @@ sig_ecdsa(const uint8_t *message, size_t message_len,
 	/* Prepare data to be signed */
 	dump("message", message, message_len);
 	SHA256Init(&ctx);
-	SHA256Update(&ctx, application, strlen(application));
+	SHA256Update(&ctx, (const u_char *)application, strlen(application));
 	SHA256Final(apphash, &ctx);
 	dump("apphash", apphash, sizeof(apphash));
 	countbuf[0] = (counter >> 24) & 0xff;
@@ -435,7 +435,7 @@ sig_ed25519(const uint8_t *message, size_t message_len,
 	/* Prepare data to be signed */
 	dump("message", message, message_len);
 	SHA256Init(&ctx);
-	SHA256Update(&ctx, application, strlen(application));
+	SHA256Update(&ctx, (const u_char *)application, strlen(application));
 	SHA256Final(apphash, &ctx);
 	dump("apphash", apphash, sizeof(apphash));