diff --git a/sink/sink20169.c b/sink/sink20169.c
index 9fb022b..0c0e1ac 100644
--- a/sink/sink20169.c
+++ b/sink/sink20169.c
@@ -275,7 +275,7 @@ int forwardMinuteBuffer(t_forwarderHandle *handle, t_minuteBuffer *buf) {
         char payload[256];
         int res = snprintf(payload, sizeof(payload),
                            "%s,valid=1,location=%s,host=%s freq=%d.%03d"
-#if OS = OpenBSD
+#if OS == OpenBSD
                            " %llu"
 #else
                            " %lu"