diff --git a/src/main/blackbox/blackbox.c b/src/main/blackbox/blackbox.c
index 8b102d1d754..332d0f3c564 100644
--- a/src/main/blackbox/blackbox.c
+++ b/src/main/blackbox/blackbox.c
@@ -285,7 +285,7 @@ static const blackboxConditionalFieldDefinition_t blackboxGpsGFields[] = {
     {"GPS_numSat",        -1, UNSIGNED, PREDICT(0),          ENCODING(UNSIGNED_VB), CONDITION(ALWAYS)},
     {"GPS_coord",          0, SIGNED,   PREDICT(HOME_COORD), ENCODING(SIGNED_VB),   CONDITION(ALWAYS)},
     {"GPS_coord",          1, SIGNED,   PREDICT(HOME_COORD), ENCODING(SIGNED_VB),   CONDITION(ALWAYS)},
-    {"GPS_altitude",      -1, UNSIGNED, PREDICT(0),          ENCODING(UNSIGNED_VB), CONDITION(ALWAYS)},
+    {"GPS_altitude",      -1, SIGNED, PREDICT(0),            ENCODING(SIGNED_VB),   CONDITION(ALWAYS)},
     {"GPS_speed",         -1, UNSIGNED, PREDICT(0),          ENCODING(UNSIGNED_VB), CONDITION(ALWAYS)},
     {"GPS_ground_course", -1, UNSIGNED, PREDICT(0),          ENCODING(UNSIGNED_VB), CONDITION(ALWAYS)},
     {"GPS_hdop",          -1, UNSIGNED, PREDICT(0),          ENCODING(UNSIGNED_VB), CONDITION(ALWAYS)},