diff --git a/demod/mod/rs41mod.c b/demod/mod/rs41mod.c
index 69a1dda..b43dbd0 100644
--- a/demod/mod/rs41mod.c
+++ b/demod/mod/rs41mod.c
@@ -768,9 +768,12 @@ static int get_PTU(gpx_t *gpx, int ofs, int pck, int valid_alt) {
         bT2 = gpx->calfrchk[0x13];
         bH  = gpx->calfrchk[0x07];
 
-        bH2 = gpx->calfrchk[0x08] && gpx->calfrchk[0x09]
-           && gpx->calfrchk[0x10] && gpx->calfrchk[0x11]
-           && gpx->calfrchk[0x12] && gpx->calfrchk[0x13]
+        bH2 = gpx->calfrchk[0x07] && gpx->calfrchk[0x08]
+           && gpx->calfrchk[0x09] && gpx->calfrchk[0x0A]
+           && gpx->calfrchk[0x0B] && gpx->calfrchk[0x0C]
+           && gpx->calfrchk[0x0D] && gpx->calfrchk[0x0E]
+           && gpx->calfrchk[0x0F] && gpx->calfrchk[0x10]
+           && gpx->calfrchk[0x11] && gpx->calfrchk[0x12]
            && gpx->calfrchk[0x2A] && gpx->calfrchk[0x2B]
            && gpx->calfrchk[0x2C] && gpx->calfrchk[0x2D]
            && gpx->calfrchk[0x2E];
diff --git a/tools/pos2nmea.pl b/tools/pos2nmea.pl
index 96dcc09..37ecedf 100755
--- a/tools/pos2nmea.pl
+++ b/tools/pos2nmea.pl
@@ -51,6 +51,8 @@ else {
 
 my $geoid = 50.0;  ## GPS ueber Ellipsoid; Geoid-Hoehe in Europa ca 40-50m
 
+$| = 1;  ## line buffering erzwingen
+
 while ($line = <$fpi>) {
 
     print STDERR $line; ## entweder: alle Zeilen ausgeben