diff --git a/Makefile b/Makefile
index 4371c63..a2fdafd 100644
--- a/Makefile
+++ b/Makefile
@@ -191,6 +191,9 @@ wasm: $(WASM_TARGET)
 $(WASM_TARGET): $(WASM_OBJECTS)
 	$(EMAR) rcs $@ $^
 
+javascript/olm_prefix.js: javascript/olm_prefix.js.in Makefile
+	sed s/@VERSION@/$(VERSION)/ javascript/olm_prefix.js.in > $@
+
 # Note that the output file we give to emcc determines the name of the
 # wasm file baked into the js, hence messing around outputting to olm.js
 # and then renaming it.
diff --git a/javascript/olm_prefix.js b/javascript/olm_prefix.js
deleted file mode 100644
index ae2d9f9..0000000
--- a/javascript/olm_prefix.js
+++ /dev/null
@@ -1,4 +0,0 @@
-var Olm = (function() {
-var olm_exports = {};
-var onInitSuccess;
-var onInitFail;
diff --git a/javascript/olm_prefix.js.in b/javascript/olm_prefix.js.in
new file mode 100644
index 0000000..76031a9
--- /dev/null
+++ b/javascript/olm_prefix.js.in
@@ -0,0 +1,7 @@
+// @license magnet:?xt=urn:btih:8e4f440f4c65981c5bf93c76d35135ba5064d8b7&dn=apache-2.0.txt Apache-2.0
+// @source: https://gitlab.matrix.org/matrix-org/olm/-/tree/@VERSION@
+
+var Olm = (function() {
+var olm_exports = {};
+var onInitSuccess;
+var onInitFail;
diff --git a/javascript/olm_suffix.js b/javascript/olm_suffix.js
index d6f72b7..dd2639a 100644
--- a/javascript/olm_suffix.js
+++ b/javascript/olm_suffix.js
@@ -34,3 +34,5 @@ if (typeof module === 'object') {
     // level wrapper class.
     module.exports = Olm;
 }
+
+// @license-end