diff --git a/src/cam.c b/src/cam.c
index d4c5a11..a68a966 100644
--- a/src/cam.c
+++ b/src/cam.c
@@ -29,7 +29,7 @@
 #define LEAP_SECONDS 5
 
 #define EARTH_RADIUS 6369000
-#define RAD_PER_DEG M_PI_2/180.0
+#define RAD_PER_DEG M_PI/180.0
 
 const cid_ssp_bm_t CID_SSP_BM_MAP[] = {
     {"CenDsrcTollingZone/ProtectedCommunicationZonesRSU",                            0x8000},