diff --git a/lib/filesystem.nix b/lib/filesystem.nix
index 6dfd273b0a55..37b60e4fe11e 100644
--- a/lib/filesystem.nix
+++ b/lib/filesystem.nix
@@ -32,17 +32,21 @@ in
       pathType /some/file.nix
       => "regular"
   */
-  pathType = path:
-    if ! pathExists path
-    # Fail irrecoverably to mimic the historic behavior of this function and
-    # the new builtins.readFileType
-    then abort "lib.filesystem.pathType: Path ${toString path} does not exist."
-    # The filesystem root is the only path where `dirOf / == /` and
-    # `baseNameOf /` is not valid. We can detect this and directly return
-    # "directory", since we know the filesystem root can't be anything else.
-    else if dirOf path == path
-    then "directory"
-    else (readDir (dirOf path)).${baseNameOf path};
+  pathType =
+    builtins.readFileType or
+    # Nix <2.14 compatibility shim
+    (path:
+      if ! pathExists path
+      # Fail irrecoverably to mimic the historic behavior of this function and
+      # the new builtins.readFileType
+      then abort "lib.filesystem.pathType: Path ${toString path} does not exist."
+      # The filesystem root is the only path where `dirOf / == /` and
+      # `baseNameOf /` is not valid. We can detect this and directly return
+      # "directory", since we know the filesystem root can't be anything else.
+      else if dirOf path == path
+      then "directory"
+      else (readDir (dirOf path)).${baseNameOf path}
+    );
 
   /*
     Whether a path exists and is a directory.