diff --git a/RX_FSK/src/RS41.cpp b/RX_FSK/src/RS41.cpp
index 6f8d637..801c402 100644
--- a/RX_FSK/src/RS41.cpp
+++ b/RX_FSK/src/RS41.cpp
@@ -862,7 +862,7 @@ int RS41::waitRXcomplete() {
 int RS41::getSubtype(char *buf, int buflen, SondeInfo *si) {
 	struct subframeBuffer *sf = (struct subframeBuffer *)si->extra;
 	if(!sf) return -1;
-	if( (sf->valid & (3<<21)) != (3<<21) ) return -1;   // or 1 instead of 3 for the first 8 chars only, as in autorx?
+	if( (sf->valid & (3<<0x21)) != (3<<0x21) ) return -1;   // or 1 instead of 3 for the first 8 chars only, as in autorx?
 	if(buflen>11) buflen=11;			    // then buflen should be capped at 9 (8+trailing \0)
 	strncpy(buf, sf->value.names.variant, buflen);
 	buf[buflen-1]=0;