diff --git a/core/src/nix/drv.sld b/core/src/nix/drv.sld
index 4d037dc..c5da1cf 100644
--- a/core/src/nix/drv.sld
+++ b/core/src/nix/drv.sld
@@ -21,7 +21,8 @@
     derivation-args derivation-env derivation-equal?
    
     derivation-serialize derivation-path-references derivation-path derivation-read read-drv-path
-    make-fixed-output-derivation make-input-addressed-derivation make-impure-derivation make-ca-derivation)
+    make-fixed-output-derivation make-input-addressed-derivation make-impure-derivation make-ca-derivation
+    modulo-hash-drv-contents)
 
   (begin
     ;; If `#t`, outputs environment variables not used by Nix, but required for compatibility with Nix's output.
@@ -106,7 +107,7 @@
         (fprintf out "#<derivation ~s ~s inputs: ~s ~s, ~s ~s ~s ~s, cached data ~S>"
           (derivation-name drv)
           (derivation-outputs drv)
-          (if was-printing-drv (map derivation-name (derivation-input-drvs)) (derivation-input-drvs drv))
+          (if was-printing-drv (map derivation-name (derivation-input-drvs drv)) (derivation-input-drvs drv))
           (derivation-input-src drv)
           (derivation-system drv)
           (derivation-builder drv)