diff --git a/lib/hyperscript/parser.sx b/lib/hyperscript/parser.sx
index be58d2b6..d1413bbd 100644
--- a/lib/hyperscript/parser.sx
+++ b/lib/hyperscript/parser.sx
@@ -3133,7 +3133,19 @@
             acc
             (let
               ((feat (parse-feat)))
-              (if (nil? feat) acc (coll-feats (append acc (list feat))))))))
+              (if
+                (nil? feat)
+                (if
+                  (at-end?)
+                  acc
+                  (error
+                    (str
+                      "Parse error: Unexpected token '"
+                      (tp-val)
+                      "' (line "
+                      (get (nth tokens p) "line")
+                      ")")))
+                (coll-feats (append acc (list feat))))))))
       (let
         ((features (coll-feats (list))))
         (if
diff --git a/shared/static/wasm/sx/hs-parser.sx b/shared/static/wasm/sx/hs-parser.sx
index be58d2b6..d1413bbd 100644
--- a/shared/static/wasm/sx/hs-parser.sx
+++ b/shared/static/wasm/sx/hs-parser.sx
@@ -3133,7 +3133,19 @@
             acc
             (let
               ((feat (parse-feat)))
-              (if (nil? feat) acc (coll-feats (append acc (list feat))))))))
+              (if
+                (nil? feat)
+                (if
+                  (at-end?)
+                  acc
+                  (error
+                    (str
+                      "Parse error: Unexpected token '"
+                      (tp-val)
+                      "' (line "
+                      (get (nth tokens p) "line")
+                      ")")))
+                (coll-feats (append acc (list feat))))))))
       (let
         ((features (coll-feats (list))))
         (if