1 files changed, 6 insertions, 3 deletions
diff --git a/src/libstore/builtins/fetchurl.cc b/src/libstore/builtins/fetchurl.cc
index f3827684b..84c7d2082 100644
--- a/src/libstore/builtins/fetchurl.cc
+++ b/src/libstore/builtins/fetchurl.cc
@@ -58,13 +58,16 @@ void builtinFetchurl(const BasicDerivation & drv, const std::string & netrcData)
         }
     };
 
+    /* We always have one output, and if it's a fixed-output derivation (as
+       checked below) it must be the only output */
+    auto & output = drv.outputs.begin()->second;
+
     /* Try the hashed mirrors first. */
-    if (getAttr("outputHashMode") == "flat")
+    if (output.hash && output.hash->method == FileIngestionMethod::Flat)
         for (auto hashedMirror : settings.hashedMirrors.get())
             try {
                 if (!hasSuffix(hashedMirror, "/")) hashedMirror += '/';
-                auto ht = parseHashTypeOpt(getAttr("outputHashAlgo"));
-                auto h = Hash(getAttr("outputHash"), ht);
+                auto & h = output.hash->hash;
                 fetch(hashedMirror + printHashType(h.type) + "/" + h.to_string(Base16, false));
                 return;
             } catch (Error & e) {