diff --git a/libraries/AP_Common/AP_Var.cpp b/libraries/AP_Common/AP_Var.cpp
index 34fabce6d5..ffe09e658a 100644
--- a/libraries/AP_Common/AP_Var.cpp
+++ b/libraries/AP_Common/AP_Var.cpp
@@ -338,7 +338,7 @@ AP_Var::key(void)
     if (_group) {                   // group members don't have keys
         return k_key_none;
     }
-    if (_key && k_key_not_located) {    // if not located, key is in memory
+    if (_key & k_key_not_located) {    // if not located, key is in memory
         return _key & k_key_mask;
     }