diff --git a/doerg/package.nix b/doerg/package.nix
index d2a1715..978b948 100644
--- a/doerg/package.nix
+++ b/doerg/package.nix
@@ -6,7 +6,8 @@
 }:
 
 let
-  # mkCljBin sans fake-git.
+  # mkCljBin sans fake-git. We don't need it, and I don't want it in
+  # my dev shell.
   mkCljBin' = args: (mkCljBin args).overrideAttrs (final: prev: {
     nativeBuildInputs =
       builtins.filter
diff --git a/doerg/src/net/deertopia/doerg/config.clj b/doerg/src/net/deertopia/doerg/config.clj
index 54e753f..49cdf03 100644
--- a/doerg/src/net/deertopia/doerg/config.clj
+++ b/doerg/src/net/deertopia/doerg/config.clj
@@ -16,4 +16,4 @@
 
 (def ^:dynamic *cfg* default)
 
-(s/def ::ibm-plex-web string?)
+(s/def ::ibm-plex-web #(instance? java.io.File %))