diff --git a/lib/fsk4hf/chkcrc12.f90 b/lib/fsk4hf/chkcrc12.f90
new file mode 100644
index 000000000..a177fa110
--- /dev/null
+++ b/lib/fsk4hf/chkcrc12.f90
@@ -0,0 +1,27 @@
+subroutine chkcrc12(decoded,nbadcrc)
+
+  use crc
+  integer*1 decoded(84)
+  integer*1, target:: i1Dec8BitBytes(11)
+
+! Check the CRC
+! Collapse 84 decoded bits to 11 bytes. Bytes 1-9 are the message,
+! byte 10 and first half of byte 11 is the crc
+  do ibyte=1,9
+      itmp=0
+    do ibit=1,8
+      itmp=ishft(itmp,1)+iand(1,decoded((ibyte-1)*8+ibit))
+    enddo
+    i1Dec8BitBytes(ibyte)=itmp
+  enddo
+
+! Pack the crc into bytes 10 and 11 for crc12_check
+  i1Dec8BitBytes(10)=decoded(73)*8 + decoded(74)*4 + decoded(75)*2 + decoded(76)
+  i1Dec8BitBytes(11)=decoded(77)*128 + decoded(78)*64 +                      &
+       decoded(79)*32 + decoded(80)*16 + decoded(81)*8 + decoded(82)*4 +   &
+       decoded(83)*2 + decoded(84)
+  nbadcrc=1
+  if( crc12_check(c_loc (i1Dec8BitBytes), 11) ) nbadcrc=0
+  
+  return
+end subroutine chkcrc12