diff --git a/hclsyntax/spec.md b/hclsyntax/spec.md
index 3fc5f5f..550bd93 100644
--- a/hclsyntax/spec.md
+++ b/hclsyntax/spec.md
@@ -273,7 +273,7 @@ tuple = "[" (
 object = "{" (
     (objectelem ("," objectelem)* ","?)?
 ) "}";
-objectelem = (Identifier | Expression) "=" Expression;
+objectelem = (Identifier | Expression) ("=" | ":") Expression;
 ```
 
 Only tuple and object values can be directly constructed via native syntax.