diff --git a/js/compiler/compiler.js b/js/compiler/compiler.js
index 69bcf56..e9edbb0 100644
--- a/js/compiler/compiler.js
+++ b/js/compiler/compiler.js
@@ -129,9 +129,11 @@ var modifiedSourceActions = {
       label + ', ' + JSON.stringify(formals) + ');';
   },
 
-  FieldDeclarationStatement: function(_field, memberExpr, _eq, initExpr, sc) {
+  FieldDeclarationStatement: function(_field, memberExpr, _eq, maybeInitExpr, sc) {
     return 'Syndicate.Actor.declareField(' + memberExpr.memberObjectExpr.asES5 + ', ' +
-      memberExpr.memberPropExpr.asES5 + ', ' + initExpr.asES5 + ')' +
+      memberExpr.memberPropExpr.asES5 + ', ' +
+      (maybeInitExpr.numChildren === 1 ? maybeInitExpr.asES5 : 'undefined') +
+      ')' +
       sc.interval.contents;
   },
 
diff --git a/js/compiler/syndicate.ohm b/js/compiler/syndicate.ohm
index b91a487..66c5899 100644
--- a/js/compiler/syndicate.ohm
+++ b/js/compiler/syndicate.ohm
@@ -31,7 +31,7 @@ Syndicate <: ES5 {
   AssertionTypeDeclarationStatement
     = (assertion | message) type identifier "(" FormalParameterList ")" ("=" stringLiteral)? #(sc)
 
-  FieldDeclarationStatement = field MemberExpression "=" AssignmentExpression<withIn> #(sc)
+  FieldDeclarationStatement = field MemberExpression ("=" AssignmentExpression<withIn>)? #(sc)
   MemberExpression += field MemberExpression -- fieldRefExp
   UnaryExpression += delete field MemberExpression -- fieldDelExp