diff --git a/src/Ampersand/Basics/String.hs b/src/Ampersand/Basics/String.hs
index 74746a788..763253bc1 100644
--- a/src/Ampersand/Basics/String.hs
+++ b/src/Ampersand/Basics/String.hs
@@ -89,7 +89,7 @@ escapeIdentifier (Text1 c0 cs) =
 --   characters of an identifier, a boolean is required that tells if this is the
 --   first character.
 isSafeIdChar :: Bool -> Char -> Bool
-isSafeIdChar isFirst c = isLower c || isUpper c || (not isFirst && isAlphaNum c)
+isSafeIdChar isFirst c = isLower c || isUpper c || (not isFirst && (isAlphaNum c || c == '_'))
 
 toText1Unsafe :: Text -> Text1
 toText1Unsafe txt = case T.uncons txt of