diff --git a/package.json b/package.json
index f99f5c0..416177f 100644
--- a/package.json
+++ b/package.json
@@ -24,7 +24,7 @@
     "normalize-path": "^3.0.0"
   },
   "peerDependencies": {
-    "mem-fs": "^2.0.0"
+    "mem-fs": "^1.2.0 || ^2.0.0"
   },
   "peerDependenciesMeta": {
     "mem-fs": {