diff --git a/src/osdp_phy.c b/src/osdp_phy.c
index ff4743b..dc469fe 100644
--- a/src/osdp_phy.c
+++ b/src/osdp_phy.c
@@ -346,7 +346,6 @@ static int phy_check_header(struct osdp_pd *pd)
 				buf[0] = OSDP_PKT_MARK;
 				buf[1] = OSDP_PKT_SOM;
 				pd->packet_buf_len = 2;
-				pd->packet_scan_skip--;
 				SET_FLAG(pd, PD_FLAG_PKT_HAS_MARK);
 			} else {
 				buf[0] = OSDP_PKT_SOM;
@@ -354,7 +353,8 @@ static int phy_check_header(struct osdp_pd *pd)
 				CLEAR_FLAG(pd, PD_FLAG_PKT_HAS_MARK);
 			}
 			break;
-		} else {
+		}
+		if (cur_byte != OSDP_PKT_MARK) {
 			pd->packet_scan_skip++;
 		}
 		prev_byte = cur_byte;