diff --git a/src/runtime/os_js.go b/src/runtime/os_js.go
new file mode 100644
index 000000000..422b1d322
--- /dev/null
+++ b/src/runtime/os_js.go
@@ -0,0 +1,5 @@
+// +build js
+
+package runtime
+
+const GOOS = "js"
diff --git a/src/runtime/os_linux.go b/src/runtime/os_linux.go
new file mode 100644
index 000000000..ab43c3a47
--- /dev/null
+++ b/src/runtime/os_linux.go
@@ -0,0 +1,5 @@
+// +build linux
+
+package runtime
+
+const GOOS = "linux"