diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index 969391725..73817dbdd 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -991,7 +991,7 @@ static void prim_derivationStrict(EvalState & state, const Pos & pos, Value * *
     bool contentAddressed = false;
     bool isImpure = false;
     std::optional<std::string> outputHash;
-    std::optional<std::string> outputHashAlgo;
+    std::string outputHashAlgo;
     std::optional<FileIngestionMethod> ingestionMethod;
 
     StringSet outputs;
@@ -1190,8 +1190,7 @@ static void prim_derivationStrict(EvalState & state, const Pos & pos, Value * *
                 .errPos = posDrvName
             });
 
-        std::optional<HashType> ht = parseHashTypeOpt(outputHashAlgo.value_or("sha256"));
-        Hash h = newHashAllowEmpty(*outputHash, ht);
+        auto h = newHashAllowEmpty(*outputHash, parseHashTypeOpt(outputHashAlgo));
 
         auto method = ingestionMethod.value_or(FileIngestionMethod::Flat);
         auto outPath = state.store->makeFixedOutputPath(method, h, drvName);
@@ -1212,7 +1211,7 @@ static void prim_derivationStrict(EvalState & state, const Pos & pos, Value * *
                 .errPos = posDrvName
             });
 
-        auto ht = parseHashType(outputHashAlgo.value_or("sha256"));
+        auto ht = parseHashTypeOpt(outputHashAlgo).value_or(htSHA256);
         auto method = ingestionMethod.value_or(FileIngestionMethod::Recursive);
 
         for (auto & i : outputs) {
diff --git a/tests/ca/content-addressed.nix b/tests/ca/content-addressed.nix
index d328fc92c..1be3eeb6e 100644
--- a/tests/ca/content-addressed.nix
+++ b/tests/ca/content-addressed.nix
@@ -64,8 +64,7 @@ rec {
   dependentFixedOutput = mkDerivation {
     name = "dependent-fixed-output";
     outputHashMode = "recursive";
-    outputHashAlgo = "sha256";
-    outputHash = "sha256-QvtAMbUl/uvi+LCObmqOhvNOapHdA2raiI4xG5zI5pA=";
+    outputHash = "sha512-7aJcmSuEuYP5tGKcmGY8bRr/lrCjJlOxP2mIUjO/vMQeg6gx/65IbzRWES8EKiPDOs9z+wF30lEfcwxM/cT4pw==";
     buildCommand = ''
       cat ${dependentCA}/dep
       echo foo > $out