diff --git a/vm/vm.go b/vm/vm.go
index 9f3bcb0..b6a3bea 100644
--- a/vm/vm.go
+++ b/vm/vm.go
@@ -942,7 +942,9 @@ func walkTernary(ctx expr.EvalContext, includer expr.Includer, node *expr.TriNod
 			return value.NewBoolValue(false), true
 
 		default:
-			u.Warnf("between not implemented for type %s %#v", a.Type().String(), node)
+			// Unsupported left-hand types (maps, slices, strings) don't match, silently like evalBinary:
+			// a filter is evaluated per entity, so a warning here fires once per entity.
+			return nil, false
 		}
 	default:
 		u.Warnf("ternary node walk not implemented for node %#v", node)
diff --git a/vm/vm_test.go b/vm/vm_test.go
index e0c22ea..09567f8 100644
--- a/vm/vm_test.go
+++ b/vm/vm_test.go
@@ -137,6 +137,9 @@ var (
 		vmtall(`10 BETWEEN 20 AND true`, nil, parseOk, evalError),
 		vmt(`created BETWEEN "12/18/2015" AND "12/18/2050"`, true, noError),
 		vmt(`created BETWEEN "now-50w" AND "12/18/2050"`, true, noError),
+		vmtall(`mt BETWEEN "12/18/2015" AND "12/18/2050"`, nil, parseOk, evalError),
+		vmtall(`mt NOT BETWEEN "12/18/2015" AND "12/18/2050"`, nil, parseOk, evalError),
+		vmtall(`urls BETWEEN "a" AND "z"`, nil, parseOk, evalError),
 
 		// In:  Multi Arg Tests
 		vmtall(`10 IN ("a","b",10, 4.5)`, true, parseOk, evalError),