diff --git a/channels/chan_iax2.c b/channels/chan_iax2.c
index 16c911d6a9..f76a471ec8 100755
--- a/channels/chan_iax2.c
+++ b/channels/chan_iax2.c
@@ -2893,10 +2893,13 @@ static unsigned int calc_timestamp(struct chan_iax2_pvt *p, unsigned int ts, str
 				* next multiple of frame size (so our
 				* silent periods are multiples of
 				* frame size too) */
-				int diff = ms % (f->samples / 8);
-				if(diff)
-				    ms += f->samples/8 - diff;
-
+				int adj = f->samples / 8;
+				if (adj) {
+					int diff = ms % adj;
+					if(diff)
+						ms += adj - diff;
+				}
+				
 				p->nextpred = ms;
 				p->notsilenttx = 1;
 			}