diff --git a/lib/fluxsink/scpfluxsink.cc b/lib/fluxsink/scpfluxsink.cc
index 697dcf0e..42e77c88 100644
--- a/lib/fluxsink/scpfluxsink.cc
+++ b/lib/fluxsink/scpfluxsink.cc
@@ -85,6 +85,12 @@ public:
 		trackdataWriter.seekToEnd();
 		int strack = strackno(cylinder, head);
 
+                if (strack >= std::size(_fileheader.track)) {
+                    std::cout << fmt::format("SCP: cannot write track {} head {}, "
+                            "there are not not enough Track Data Headers.\n",
+                            cylinder, head);
+                    return;
+                }
 		ScpTrack trackheader = {0};
 		trackheader.header.track_id[0] = 'T';
 		trackheader.header.track_id[1] = 'R';