1 files changed, 4 insertions, 1 deletions
diff --git a/src/path.c b/src/path.c
index 340f8c7..85233d6 100644
--- a/src/path.c
+++ b/src/path.c
@@ -84,7 +84,10 @@ path *path_init(double *pos, double *dir, double T0, double range, double theta0
             dz[i] = (s[i]-s[i-1])*cos(theta);
 
             /* Calculate total energy */
-            t[i] = t[i-1] + (s[i]-s[i-1])/(beta[i]*SPEED_OF_LIGHT);
+            if (beta[i] > 0)
+                t[i] = t[i-1] + (s[i]-s[i-1])/(beta[i]*SPEED_OF_LIGHT);
+            else
+                t[i] = t[i-1];
 
             x[i] = x[i-1] + dx[i];
             y[i] = y[i-1] + dy[i];