diff --git a/src/main/java/vdm/VDMGenerator.java b/src/main/java/vdm/VDMGenerator.java
index 92dc019d..2956a858 100644
--- a/src/main/java/vdm/VDMGenerator.java
+++ b/src/main/java/vdm/VDMGenerator.java
@@ -72,7 +72,7 @@ public List<Path> generate() throws IOException {
               + "\""));
         } else {
           lines.add(segment(count++, "SkipAhead", "skip", "starttick \"" + (previousEndTick + 1)
-              + "\"", "skiptotick \"" + (tick.getStart() - 500) + "\""));
+              + "\"", "skiptotick \"" + Math.max(0, tick.getStart() - 500) + "\""));
         }
         String command = "startrecording";
         if (tick.getType().equals(Tick.EXEC_RECORD_SEGMENT)) {