diff --git a/lisp/env.el b/lisp/env.el
index a9d1d27e1ee..faafcb6250f 100644
--- a/lisp/env.el
+++ b/lisp/env.el
@@ -204,8 +204,8 @@ parameter.
 Otherwise, this function searches `process-environment' for
 VARIABLE.  If it is not found there, then it continues the search
 in the environment list of the selected frame."
-  (interactive (list (read-envvar-name "Get environment variable: " t)))
   (declare (side-effect-free t))
+  (interactive (list (read-envvar-name "Get environment variable: " t)))
   (let ((value (getenv-internal (if (multibyte-string-p variable)
 				    (encode-coding-string
 				     variable locale-coding-system)