diff --git a/faup1090.c b/faup1090.c
index 425bc92..e476a7e 100644
--- a/faup1090.c
+++ b/faup1090.c
@@ -204,7 +204,6 @@ int main(int argc, char **argv) {
     // Set up output connection on stdout
     fatsv_output = makeFatsvOutputService();
     createGenericClient(fatsv_output, STDOUT_FILENO);
-    writeFATSVHeader();
 
     // Run it until we've lost either connection
     while (!Modes.exit && beast_input->connections && fatsv_output->connections) {
diff --git a/net_io.c b/net_io.c
index 3bc2f85..09547b7 100644
--- a/net_io.c
+++ b/net_io.c
@@ -1863,26 +1863,7 @@ __attribute__ ((format (printf,4,5))) static char *appendFATSV(char *p, char *en
 }
 
 #define TSV_MAX_PACKET_SIZE 600
-#define TSV_VERSION 3
-
-void writeFATSVHeader()
-{
-    char *p = prepareWrite(&Modes.fatsv_out, TSV_MAX_PACKET_SIZE);
-    if (!p)
-        return;
-
-    char *end = p + TSV_MAX_PACKET_SIZE;
-
-    p = appendFATSV(p, end, "clock",        "%"   PRIu64, mstime() / 1000);
-    p = appendFATSV(p, end, "tsv_version",  "%u", TSV_VERSION);
-    --p; // remove last tab
-    p = safe_snprintf(p, end, "\n");
-
-    if (p <= end)
-        completeWrite(&Modes.fatsv_out, p);
-    else
-        fprintf(stderr, "fatsv: output too large (max %d, overran by %d)\n", TSV_MAX_PACKET_SIZE, (int) (p - end));
-}
+#define TSV_VERSION "4E"
 
 static void writeFATSVPositionUpdate(float lat, float lon, float alt)
 {
@@ -1901,6 +1882,7 @@ static void writeFATSVPositionUpdate(float lat, float lon, float alt)
 
     char *end = p + TSV_MAX_PACKET_SIZE;
 
+    p = appendFATSV(p, end, "_v",     "%s", TSV_VERSION);
     p = appendFATSV(p, end, "clock",  "%" PRIu64, messageNow() / 1000);
     p = appendFATSV(p, end, "type",   "%s",       "location_update");
     p = appendFATSV(p, end, "lat",    "%.5f",     lat);
@@ -1924,6 +1906,7 @@ static void writeFATSVEventMessage(struct modesMessage *mm, const char *datafiel
 
     char *end = p + TSV_MAX_PACKET_SIZE;
 
+    p = appendFATSV(p, end, "_v",    "%s", TSV_VERSION);
     p = appendFATSV(p, end, "clock", "%" PRIu64, messageNow() / 1000);
     p = appendFATSV(p, end, (mm->addr & MODES_NON_ICAO_ADDRESS) ? "otherid" : "hexid", "%06X", mm->addr & 0xFFFFFF);
     if (mm->addrtype != ADDR_ADSB_ICAO) {
@@ -2174,6 +2157,7 @@ static void writeFATSV()
             return;
         char *end = p + TSV_MAX_PACKET_SIZE;
 
+        p = appendFATSV(p, end, "_v",    "%s", TSV_VERSION);
         p = appendFATSV(p, end, "clock", "%" PRIu64, messageNow() / 1000);
         p = appendFATSV(p, end, (a->addr & MODES_NON_ICAO_ADDRESS) ? "otherid" : "hexid", "%06X", a->addr & 0xFFFFFF);
 
diff --git a/net_io.h b/net_io.h
index 0dd3ea8..2c39f6f 100644
--- a/net_io.h
+++ b/net_io.h
@@ -87,8 +87,6 @@ void modesInitNet(void);
 void modesQueueOutput(struct modesMessage *mm, struct aircraft *a);
 void modesNetPeriodicWork(void);
 
-void writeFATSVHeader();
-
 // TODO: move these somewhere else
 char *generateAircraftJson(const char *url_path, int *len);
 char *generateStatsJson(const char *url_path, int *len);