diff --git a/candm.h b/candm.h
index 7e94caa..f3eb433 100644
--- a/candm.h
+++ b/candm.h
@@ -518,7 +518,7 @@ typedef struct {
 
 typedef struct {
   IPAddr ip_addr;
-  uint16_t poll;
+  int16_t poll;
   uint16_t stratum;
   uint16_t state;
   uint16_t mode;
diff --git a/client.c b/client.c
index deb7ead..303fe4a 100644
--- a/client.c
+++ b/client.c
@@ -1733,8 +1733,8 @@ process_cmd_sources(char *line)
   double orig_latest_meas, latest_meas, latest_meas_err;
   IPAddr ip_addr;
   uint32_t latest_meas_ago;
-  uint16_t poll, stratum;
-  uint16_t state, mode, flags, reachability;
+  int16_t poll;
+  uint16_t stratum, state, mode, flags, reachability;
   char hostname_buf[50];
 
   /* Check whether to output verbose headers */