diff --git a/meshtastic/atak.proto b/meshtastic/atak.proto
index 182d739..c44479f 100644
--- a/meshtastic/atak.proto
+++ b/meshtastic/atak.proto
@@ -237,7 +237,7 @@ message PLI {
   /*
    * Altitude (ATAK prefers HAE)
    */
-  uint32 altitude = 3;
+  int32 altitude = 3;
 
   /*
    * Speed
@@ -248,4 +248,4 @@ message PLI {
    * Course in degrees
    */
   uint32 course = 5;  
-}
\ No newline at end of file
+}