diff --git a/README.md b/README.md
index 0bc155e407..a15bdd424e 100644
--- a/README.md
+++ b/README.md
@@ -185,7 +185,9 @@ helper functions for printing and serializing this data. For a type named `t`, t
 for a type named something else like `q`, it will be `show_q`.
 
 #### Source Maps
-`js_of_ocaml` does support source maps and has some other flags that might be useful. If you experiment with those and get them to work, please update this README with some notes.
+Source maps for `js_of_ocaml` should be configured when making locally with the dev profile (`make`). This is configured using the env stanzas present in the `dune` files for each top-level directory.
+
+Since source maps are generated browser developer tools should show reason code in the debugger and source tree. Stack traces should also include reason line numbers.
 
 #### Debug Mode
 If Hazel is hanging on load or when you perform certain actions, you can load into Debug Mode by appending `#debug` to the URL and reloading. From there, you have some buttons that will change settings or reset local storage. Refresh without the `#debug` flag and hopefully you can resolve the situation from there.
diff --git a/src/haz3lcore/dune b/src/haz3lcore/dune
index 6a2a51984d..77e2ca3fe1 100644
--- a/src/haz3lcore/dune
+++ b/src/haz3lcore/dune
@@ -3,9 +3,7 @@
 (library
  (name haz3lcore)
  (libraries util sexplib unionFind uuidm virtual_dom yojson core)
- (js_of_ocaml
-  (flags
-   (:include js-of-ocaml-flags-%{profile})))
+ (js_of_ocaml)
  (preprocess
   (pps
    ppx_yojson_conv
@@ -14,10 +12,10 @@
    ppx_sexp_conv
    ppx_deriving.show)))
 
-(rule
- (write-file
-  js-of-ocaml-flags-dev
-  "(:standard --debuginfo --noinline --dynlink --linkall --sourcemap)"))
-
-(rule
- (write-file js-of-ocaml-flags-release "(:standard)"))
+(env
+ (dev
+  (js_of_ocaml
+   (flags :standard --debuginfo --noinline --dynlink --linkall --sourcemap)))
+ (release
+  (js_of_ocaml
+   (flags :standard))))
diff --git a/src/haz3lschool/dune b/src/haz3lschool/dune
index d9c50213a5..a9f7575c78 100644
--- a/src/haz3lschool/dune
+++ b/src/haz3lschool/dune
@@ -13,3 +13,11 @@
  (libraries ppx_yojson_conv.expander haz3lcore haz3lschool)
  (preprocess
   (pps ppx_yojson_conv ppx_let ppx_sexp_conv ppx_deriving.show)))
+
+(env
+ (dev
+  (js_of_ocaml
+   (flags :standard --debuginfo --noinline --dynlink --linkall --sourcemap)))
+ (release
+  (js_of_ocaml
+   (flags :standard))))
diff --git a/src/haz3lweb/dune b/src/haz3lweb/dune
index 4874cbf066..8d25155dc5 100644
--- a/src/haz3lweb/dune
+++ b/src/haz3lweb/dune
@@ -17,9 +17,7 @@
   haz3lschool
   pretty
   omd)
- (js_of_ocaml
-  (flags
-   (:include js-of-ocaml-flags-%{profile})))
+ (js_of_ocaml)
  (preprocess
   (pps
    ppx_yojson_conv
@@ -48,9 +46,7 @@
   haz3lschool
   pretty
   omd)
- (js_of_ocaml
-  (flags
-   (:include js-of-ocaml-flags-%{profile})))
+ (js_of_ocaml)
  (preprocess
   (pps
    js_of_ocaml-ppx
@@ -64,9 +60,6 @@
  (modules Main)
  (libraries ppx_yojson_conv.expander haz3lweb)
  (modes js)
- (js_of_ocaml
-  (flags
-   (:include js-of-ocaml-flags-%{profile})))
  (preprocess
   (pps
    ppx_yojson_conv
@@ -86,15 +79,7 @@
 (env
  (dev
   (js_of_ocaml
-   (flags (:standard))))
+   (flags :standard --debuginfo --noinline --dynlink --linkall --sourcemap)))
  (release
   (js_of_ocaml
    (flags (:standard)))))
-
-(rule
- (write-file
-  js-of-ocaml-flags-dev
-  "(:standard --debuginfo --noinline --dynlink --linkall --sourcemap)"))
-
-(rule
- (write-file js-of-ocaml-flags-release "(:standard)"))
diff --git a/src/pretty/dune b/src/pretty/dune
index 8ad0954572..868d03defc 100644
--- a/src/pretty/dune
+++ b/src/pretty/dune
@@ -5,3 +5,11 @@
  (libraries util sexplib)
  (preprocess
   (pps ppx_let ppx_sexp_conv)))
+
+(env
+ (dev
+  (js_of_ocaml
+   (flags :standard --debuginfo --noinline --dynlink --linkall --sourcemap)))
+ (release
+  (js_of_ocaml
+   (flags :standard))))
diff --git a/src/util/dune b/src/util/dune
index 868e2e0fb9..889c95bd2c 100644
--- a/src/util/dune
+++ b/src/util/dune
@@ -1,9 +1,7 @@
 (library
  (name util)
  (libraries re base ptmap incr_dom virtual_dom yojson)
- (js_of_ocaml
-  (flags
-   (:include js-of-ocaml-flags-%{profile})))
+ (js_of_ocaml)
  (preprocess
   (pps
    ppx_yojson_conv
@@ -12,10 +10,10 @@
    ppx_sexp_conv
    ppx_deriving.show)))
 
-(rule
- (write-file
-  js-of-ocaml-flags-dev
-  "(:standard --debuginfo --noinline --dynlink --linkall --sourcemap)"))
-
-(rule
- (write-file js-of-ocaml-flags-release "(:standard)"))
+(env
+ (dev
+  (js_of_ocaml
+   (flags :standard --debuginfo --noinline --dynlink --linkall --sourcemap)))
+ (release
+  (js_of_ocaml
+   (flags :standard))))