diff --git a/afsk/main.c b/afsk/main.c
index 9cbabf62..496ff7bb 100644
--- a/afsk/main.c
+++ b/afsk/main.c
@@ -1605,7 +1605,7 @@ void get_tlm_fox() {
     }
     
     if (mode == BPSK) {  // wod field experiments
-      long val = 31234;
+      unsigned long val = 31234;
       encodeA(b, 63 + head_offset, 0xff & val); 
       encodeA(b, 64 + head_offset, (0xff00 & val) >> 8); 
       encodeA(b, 65 + head_offset, (0xff0000 & val) >> 16);