diff --git a/src/mux_h1.c b/src/mux_h1.c
index c511cfede..fb1363bc0 100644
--- a/src/mux_h1.c
+++ b/src/mux_h1.c
@@ -2630,7 +2630,7 @@ static int h1_send_error(struct h1c *h1c)
 	}
 
 	if (h1c->state == H1_CS_EMBRYONIC) {
-		BUG_ON(h1c->h1s == NULL || h1s_sc(h1c->h1s) == NULL);
+		BUG_ON(h1c->h1s == NULL || h1s_sc(h1c->h1s) != NULL);
 		TRACE_DEVEL("Abort embryonic H1S", H1_EV_H1C_ERR, h1c->conn, h1c->h1s);
 		h1s_destroy(h1c->h1s);
 	}