diff --git a/src/beowulf/bootstrap.clj b/src/beowulf/bootstrap.clj
index 79e6a23..d7c3595 100644
--- a/src/beowulf/bootstrap.clj
+++ b/src/beowulf/bootstrap.clj
@@ -19,8 +19,8 @@
   be Lisp 1.5's EQuivalent of `SETQ`), possibly by other things."
   (atom NIL))
 
-(def ^:dynamic *trace?*
-  "Whether or not to trace `EVAL`."
+(def ^:dynamic *options*
+  "Command line options from invocation."
   false)
 
 (defn NULL
@@ -304,7 +304,8 @@
   See page 13 of the Lisp 1.5 Programmers Manual."
   [expr env]
   (cond
-    *trace?* (traced-eval expr env)
+    (true? (:trace *options*))
+    (traced-eval expr env)
     (=
       (ATOM? expr) 'T)
     (CDR (ASSOC expr env))
diff --git a/src/beowulf/core.clj b/src/beowulf/core.clj
index b57464a..6835742 100644
--- a/src/beowulf/core.clj
+++ b/src/beowulf/core.clj
@@ -1,5 +1,5 @@
 (ns beowulf.core
-  (:require [beowulf.bootstrap :refer [EVAL oblist *trace?*]]
+  (:require [beowulf.bootstrap :refer [EVAL oblist *options*]]
             [beowulf.read :refer [READ]]
             [clojure.java.io :as io]
             [clojure.pprint :refer [pprint]]
@@ -40,6 +40,7 @@
             data
             (case (:cause data)
               :parse-failure (println (:failure data))
+              :strict nil ;; the message, which has already been printed, is enough.
               :quit (throw e)
               ;; default
               (pprint data))))))
@@ -60,7 +61,7 @@
         (if (:errors args)
           (apply str (interpose "; " (:errors args))))
         "\nSprecan 'quit' tó laéfan\n"))
-    (binding [*trace?* (true? (:trace (:options args)))]
+    (binding [*options* (:options args)]
       (try
         (repl (str (:prompt (:options args)) " "))
         (catch
diff --git a/src/beowulf/read.clj b/src/beowulf/read.clj
index e8a7848..66d22da 100644
--- a/src/beowulf/read.clj
+++ b/src/beowulf/read.clj
@@ -1,5 +1,6 @@
 (ns beowulf.read
-  (:require [clojure.math.numeric-tower :refer [expt]]
+  (:require [beowulf.bootstrap :refer [*options*]]
+            [clojure.math.numeric-tower :refer [expt]]
             [clojure.string :refer [starts-with? upper-case]]
             [instaparse.core :as i]
             [beowulf.cons-cell :refer [make-beowulf-list make-cons-cell NIL]]))
@@ -24,7 +25,7 @@
 
       ;; mexprs. I'm pretty clear that Lisp 1.5 could never read these,
       ;; but it's a convenience.
-      "mexpr := λexpr | fncall | defn | cond | mvar;
+      "mexpr := λexpr | fncall | defn | cond | mvar | mexpr comment;
       λexpr := λ lsqb bindings semi-colon body rsqb;
       λ := 'λ';
       bindings := lsqb args rsqb;
@@ -41,9 +42,12 @@
       mvar := #'[a-z]+';
       semi-colon := ';';"
 
+      ;; comments. I'm pretty confident Lisp 1.5 did NOT have these.
+      "comment := opt-space <';;'> #'[^\\n\\r]*';"
+
       ;; sexprs. Note it's not clear to me whether Lisp 1.5 had the quote macro,
       ;; but I've included it on the basis that it can do little harm.
-      "sexpr := quoted-expr | atom | number | dotted-pair | list;
+      "sexpr := quoted-expr | atom | number | dotted-pair | list | sexpr comment;
       list := lpar sexpr rpar | lpar (sexpr sep)* rpar | lpar (sexpr sep)* dot-terminal;
       dotted-pair := lpar dot-terminal ;
       dot := '.';
@@ -95,6 +99,11 @@
                   (= context :mexpr)
                   [:quoted-expr p]
                   p)
+          :comment (if
+                     (:strict *options*)
+                     (throw
+                       (ex-info "Cannot parse comments in strict mode"
+                                {:cause :strict})))
           :dotted-pair (if
                          (= context :mexpr)
                          [:fncall
@@ -103,7 +112,12 @@
                            (simplify (nth p 1) context)
                            (simplify (nth p 2) context)]]
                          (map simplify p))
-          :mexpr (simplify (second p) :mexpr)
+          :mexpr (if
+                   (:strict *options*)
+                   (throw
+                     (ex-info "Cannot parse meta expressions in strict mode"
+                              {:cause :strict}))
+                   (simplify (second p) :mexpr))
           :list (if
                   (= context :mexpr)
                   [:fncall
@@ -115,7 +129,6 @@
     p)))
 
 
-
 ;; # From Lisp 1.5 Programmers Manual, page 10
 ;; Note that I've retyped much of this, since copy/pasting out of PDF is less
 ;; than reliable. Any typos are mine. Quote starts [[
diff --git a/test/beowulf/mexpr_test.clj b/test/beowulf/mexpr_test.clj
index 3500875..f7d9dbb 100644
--- a/test/beowulf/mexpr_test.clj
+++ b/test/beowulf/mexpr_test.clj
@@ -1,6 +1,7 @@
 (ns beowulf.mexpr-test
   (:require [clojure.test :refer :all]
-            [beowulf.read :refer [parse simplify generate]]))
+            [beowulf.bootstrap :refer [*options*]]
+            [beowulf.read :refer [parse simplify generate gsp]]))
 
 ;; These tests are taken generally from the examples on page 10 of
 ;; Lisp 1.5 Programmers Manual:
@@ -64,3 +65,10 @@
                        (parse "label[ff;λ[[x];[atom[x]->x; T->ff[car[x]]]]]"))))]
       (is (= actual expected)))))
 
+(deftest strict-tests
+  (testing "Strict feature"
+    (binding [*options* {:strict true}]
+      (is (thrown-with-msg?
+            Exception
+            #"Cannot parse meta expressions in strict mode"
+            (gsp "label[ff;λ[[x];[atom[x]->x; T->ff[car[x]]]]]"))))))
diff --git a/test/beowulf/sexpr_test.clj b/test/beowulf/sexpr_test.clj
index 98d3358..fe665a1 100644
--- a/test/beowulf/sexpr_test.clj
+++ b/test/beowulf/sexpr_test.clj
@@ -2,7 +2,8 @@
   (:require [clojure.math.numeric-tower :refer [abs]]
             [clojure.test :refer :all]
             [beowulf.cons-cell :refer :all]
-            [beowulf.read :refer [parse simplify generate]]))
+            [beowulf.bootstrap :refer [*options*]]
+            [beowulf.read :refer [parse simplify generate gsp]]))
 
 ;; broadly, sexprs should be homoiconic
 
@@ -24,6 +25,32 @@
           actual (generate (simplify (parse (str expected))))]
       (is (= actual expected)))))
 
+(deftest comment-tests
+  (testing "Reading comments"
+    (let [expected 'A
+          actual (gsp "A ;; comment")]
+      (is (= actual expected)))
+    (let [expected 10
+          actual (gsp "10 ;; comment")]
+      (is (= actual expected)))
+    (let [expected 2/5
+          actual (gsp "4E-1 ;; comment")]
+      (is (= actual expected)))
+    (let [expected "(A B C)"
+          actual (print-str (gsp "(A ;; comment
+                      B C)"))]
+      (is (= actual expected)
+          "Really important that comments work inside lists"))
+;;     ;; TODO: Currently failing and I'm not sure why
+;;     (binding [*options* {:strict true}]
+;;       (is (thrown-with-msg?
+;;             Exception
+;;             #"Cannot parse comments in strict mode"
+;;             (gsp "(A ;; comment
+;;                  B C)"))))
+    ))
+
+
 (deftest number-tests
   (testing "Reading octal numbers"
     (let [expected 1