diff --git a/Makefile b/Makefile
index 84aee6b58..7860e2e35 100644
--- a/Makefile
+++ b/Makefile
@@ -113,17 +113,11 @@ cleanmost-qcert-compiler:
 
 ## Configure
 
-runtimes/javascript/qcert_runtime.ml:
-	$(MAKE) -C runtimes/javascript
-
-compiler/lib/js_runtime.ml: runtimes/javascript/qcert_runtime.ml
-	cp runtimes/javascript/qcert_runtime.ml compiler/lib/js_runtime.ml
-
 compiler/lib/static_config.ml:
 	echo "(* This file is generated *)" > compiler/lib/static_config.ml
 	echo "let qcert_home = \"$(CURDIR)\"" >> compiler/lib/static_config.ml
 
-prepare: compiler/lib/js_runtime.ml compiler/lib/static_config.ml Makefile.coq
+prepare: compiler/lib/static_config.ml Makefile.coq
 
 configure:
 	@echo "[Q*cert] "
@@ -134,8 +128,6 @@ configure:
 clean-configure:
 
 cleanall-configure:
-	$(MAKE) -C runtimes/javascript cleanall
-	rm -rf compiler/lib/js_runtime.ml
 	rm -rf compiler/lib/static_config.ml
 	rm -f compiler/.merlin compiler/*/.merlin
 
@@ -243,9 +235,6 @@ qcert-runtimes:
 	@echo "[Q*cert] "
 	@echo "[Q*cert] Building runtimes"
 	@echo "[Q*cert] "
-ifneq ($(JAVASCRIPT),)
-	@$(MAKE) javascript-runtime
-endif
 ifneq ($(JAVA),)
 	@$(MAKE) java-runtime
 endif
@@ -253,12 +242,6 @@ ifneq ($(SPARK),)
 	@$(MAKE) spark2-runtime
 endif
 
-javascript-runtime:
-	@echo "[Q*cert] "
-	@echo "[Q*cert] JavaScript runtime"
-	@echo "[Q*cert] "
-	@$(MAKE) -C runtimes/javascript
-
 java-runtime:
 	@echo "[Q*cert] "
 	@echo "[Q*cert] Java runtime"
@@ -272,14 +255,12 @@ spark2-runtime:
 	@$(MAKE) -C runtimes/spark2
 
 clean-runtimes:
-	- @$(MAKE) -C runtimes/javascript clean
 	- @$(MAKE) -C runtimes/java clean
 	- @$(MAKE) -C runtimes/spark2 clean
 	- @rm -rf bin/lib
 	- @rm -f bin/javaRunner.jar
 
 cleanall-runtimes:
-	- @$(MAKE) -C runtimes/javascript cleanall
 	- @$(MAKE) -C runtimes/java cleanall
 	- @$(MAKE) -C runtimes/spark2 cleanall
 	- @rm -rf bin/lib
@@ -337,10 +318,7 @@ demo:
 bin/qcertJS.js:
 	@$(MAKE) qcert-javascript
 
-runtimes/javascript/qcert-runtime.js:
-	@$(MAKE) javascript-runtime
-
-qcert-demo: bin/qcertJS.js runtimes/javascript/qcert-runtime.js
+qcert-demo: bin/qcertJS.js
 	@echo "[Q*cert] "
 	@echo "[Q*cert] Compiling Web Demo in TypeScript"
 	@echo "[Q*cert] "
diff --git a/compiler/dune b/compiler/dune
index 185f72efb..7efbc3046 100644
--- a/compiler/dune
+++ b/compiler/dune
@@ -9,8 +9,9 @@
 (library
  (name qcert_lib)
  (public_name coq-qcert)
- (libraries base64 uri calendar wasm coq-qcert.assemblyscript)
-)
+ (libraries base64 uri calendar wasm
+            coq-qcert.runtime.assemblyscript
+            coq-qcert.runtime.js))
 
 (copy_files util/*.{ml,mli})
 (copy_files wasm/*.{ml,mli})
diff --git a/compiler/wasm/wasm_backend.ml b/compiler/wasm/wasm_backend.ml
index df7a74b9d..b56024cf6 100644
--- a/compiler/wasm/wasm_backend.ml
+++ b/compiler/wasm/wasm_backend.ml
@@ -21,7 +21,7 @@ end = struct
   open ImpEJson
   module Encoding = Wasm_binary_ejson.Make(ImpEJson)
 
-  let runtime = Lazy.force Assemblyscript.Runtime.wasm_ast
+  let runtime = Lazy.force Assemblyscript_runtime.wasm_ast
 
   let ejson_of_cejson = function
     | Coq_cejnull -> Coq_ejnull
diff --git a/runtimes/assemblyscript/assemblyscript.ml b/runtimes/assemblyscript/assemblyscript.ml
deleted file mode 100644
index 105814721..000000000
--- a/runtimes/assemblyscript/assemblyscript.ml
+++ /dev/null
@@ -1,11 +0,0 @@
-module Runtime = struct
-  let string = Stringified.runtime
-
-  let wasm_ast =
-    lazy (
-      let open Wasm in
-      let m = Decode.decode "runtime.wasm" string in
-      let () = Valid.check_module m in
-      m
-    )
-end
diff --git a/runtimes/assemblyscript/assemblyscript_runtime.ml b/runtimes/assemblyscript/assemblyscript_runtime.ml
new file mode 100644
index 000000000..7539d78c4
--- /dev/null
+++ b/runtimes/assemblyscript/assemblyscript_runtime.ml
@@ -0,0 +1,9 @@
+let string = Stringified.runtime
+
+let wasm_ast =
+  lazy (
+    let open Wasm in
+    let m = Decode.decode "runtime.wasm" string in
+    let () = Valid.check_module m in
+    m
+  )
diff --git a/runtimes/assemblyscript/dune b/runtimes/assemblyscript/dune
index bc95f8c23..78757fce6 100644
--- a/runtimes/assemblyscript/dune
+++ b/runtimes/assemblyscript/dune
@@ -1,6 +1,6 @@
 (library
-  (name assemblyscript)
-  (public_name coq-qcert.assemblyscript)
+  (name assemblyscript_runtime)
+  (public_name coq-qcert.runtime.assemblyscript)
   (libraries wasm))
 
 (rule ; not evaluated for package release (-p flag)
diff --git a/runtimes/assemblyscript/test_ml/dune b/runtimes/assemblyscript/test_ml/dune
index ca15013fc..186bbae00 100644
--- a/runtimes/assemblyscript/test_ml/dune
+++ b/runtimes/assemblyscript/test_ml/dune
@@ -1,3 +1,3 @@
 (tests
   (names force_wasm_ast)
-  (libraries coq-qcert.assemblyscript))
+  (libraries coq-qcert.runtime.assemblyscript))
diff --git a/runtimes/assemblyscript/test_ml/force_wasm_ast.ml b/runtimes/assemblyscript/test_ml/force_wasm_ast.ml
index a0f16ee1e..9c33ba4fb 100644
--- a/runtimes/assemblyscript/test_ml/force_wasm_ast.ml
+++ b/runtimes/assemblyscript/test_ml/force_wasm_ast.ml
@@ -1 +1 @@
-let _ = Lazy.force Assemblyscript.Runtime.wasm_ast
+let _ = Lazy.force Assemblyscript_runtime.wasm_ast
diff --git a/runtimes/javascript/.gitignore b/runtimes/javascript/.gitignore
index d908e1359..8366ba46a 100644
--- a/runtimes/javascript/.gitignore
+++ b/runtimes/javascript/.gitignore
@@ -1,2 +1 @@
 qcert-runtime.js
-qcert_runtime.ml
diff --git a/runtimes/javascript/Makefile b/runtimes/javascript/Makefile
deleted file mode 100644
index 494a2ae98..000000000
--- a/runtimes/javascript/Makefile
+++ /dev/null
@@ -1,34 +0,0 @@
-#
-# Licensed under the Apache License, Version 2.0 (the "License");
-# you may not use this file except in compliance with the License.
-# You may obtain a copy of the License at
-#
-# http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.
-#
-
-############# Shouldn't have to be changed after this
-all: qcert-runtime.js qcert_runtime.ml
-
-qcert-runtime.js: qcert-runtime-core.js qcert-runtime-tostring.js qcert-runtime-sql-date.js qcert-runtime-uri.js
-	(for i in qcert-runtime-core.js qcert-runtime-tostring.js qcert-runtime-sql-date.js qcert-runtime-uri.js; do \
-         cat $$i; \
-         done) > qcert-runtime.js
-
-qcert_runtime.ml: qcert-runtime.js
-	(echo "let runtime = {runtime|"; \
-         cat qcert-runtime.js; \
-         echo '|runtime}' \
-         ) > qcert_runtime.ml
-
-clean:
-	-rm -f qcert-runtime.js qcert_runtime.ml
-	-rm -f *~
-
-cleanall: clean
-
diff --git a/runtimes/javascript/dune b/runtimes/javascript/dune
new file mode 100644
index 000000000..51afa9f39
--- /dev/null
+++ b/runtimes/javascript/dune
@@ -0,0 +1,33 @@
+(library
+  (name js_runtime)
+  (public_name coq-qcert.runtime.js))
+
+(rule ; We promote to source dir because this file is also used from nodejs.
+  (target qcert-runtime.js)
+  (mode promote)
+  (deps
+    qcert-runtime-core.js
+    qcert-runtime-tostring.js
+    qcert-runtime-sql-date.js
+    qcert-runtime-uri.js)
+  (action
+    (with-stdout-to
+      qcert-runtime.js
+      (progn (echo "/* include: qcert-runtime-core.js */\n\n")
+             (cat qcert-runtime-core.js)
+             (echo "/* include: qcert-runtime-tostring.js */\n\n")
+             (cat qcert-runtime-tostring.js)
+             (echo "/* include: qcert-runtime-sql-date.js */\n\n")
+             (cat qcert-runtime-sql-date.js)
+             (echo "/* include: qcert-runtime-uri */\n\n")
+             (cat qcert-runtime-uri.js)))))
+
+(rule
+  (target js_runtime.ml)
+  (deps qcert-runtime.js)
+  (action
+    (with-stdout-to
+      js_runtime.ml
+      (progn (echo "let runtime = {|\n")
+             (cat qcert-runtime.js)
+             (echo "|}\n")))))