--- /dev/null
+++ b/crates/jrsonnet-evaluator/tests/suite/sjsonnet_issue_127.jsonnet
@@ -0,0 +1,6 @@
+local myFunc = function(a)
+  if (a) then "a" else "b";
+
+local b = "aaa";
+
+std.assertEqual(myFunc(b == [] || b == ['e']), "b")
--- a/crates/jrsonnet-parser/src/lib.rs
+++ b/crates/jrsonnet-parser/src/lib.rs
@@ -66,7 +66,7 @@
 			/ { expr::ParamsDesc(Rc::new(Vec::new())) }
 
 		pub rule arg(s: &ParserSettings) -> (Option<IStr>, LocExpr)
-			= quiet! { name:(s:id() _ "=" _ {s})? expr:expr(s) {(name, expr)} }
+			= quiet! { name:(s:id() _ "=" !['='] _ {s})? expr:expr(s) {(name, expr)} }
 			/ expected!("<argument>")
 
 		pub rule args(s: &ParserSettings) -> expr::ArgsDesc