diff --git a/src/hydra-queue-runner/hydra-queue-runner.cc b/src/hydra-queue-runner/hydra-queue-runner.cc
index 28ed6deb5..24f037f8d 100644
--- a/src/hydra-queue-runner/hydra-queue-runner.cc
+++ b/src/hydra-queue-runner/hydra-queue-runner.cc
@@ -333,11 +333,12 @@ unsigned int State::createBuildStep(pqxx::work & txn, time_t startTime, BuildID
 
     for (auto & [name, output] : getDestStore()->queryPartialDerivationOutputMap(step->drvPath, &*localStore))
         txn.exec_params0
-            ("insert into BuildStepOutputs (build, stepnr, name, path) values ($1, $2, $3, $4)",
+            ("insert into BuildStepOutputs (build, stepnr, name, path, contentAddressed) values ($1, $2, $3, $4, $5)",
             buildId, stepNr, name,
             output
                 ? std::optional { localStore->printStorePath(*output)}
-                : std::nullopt);
+                : std::nullopt,
+            step->drv->type().isCA());
 
     if (status == bsBusy)
         txn.exec(fmt("notify step_started, '%d\t%d'", buildId, stepNr));
@@ -409,9 +410,10 @@ int State::createSubstitutionStep(pqxx::work & txn, time_t startTime, time_t sto
     if (r.affected_rows() == 0) goto restart;
 
     txn.exec_params0
-        ("insert into BuildStepOutputs (build, stepnr, name, path) values ($1, $2, $3, $4)",
+        ("insert into BuildStepOutputs (build, stepnr, name, path, contentAddressed) values ($1, $2, $3, $4, $5)",
          build->id, stepNr, outputName,
-         localStore->printStorePath(storePath));
+         localStore->printStorePath(storePath),
+         drv.type().isCA());
 
     return stepNr;
 }
diff --git a/src/lib/Hydra/Controller/Build.pm b/src/lib/Hydra/Controller/Build.pm
index de2c204d9..4c488c13f 100644
--- a/src/lib/Hydra/Controller/Build.pm
+++ b/src/lib/Hydra/Controller/Build.pm
@@ -114,6 +114,18 @@ sub build_GET {
 
     $c->stash->{steps} = [$build->buildsteps->search({}, {order_by => "stepnr desc"})];
 
+    $c->stash->{contentAddressed} = 0;
+    # Hydra marks single outputs as CA but currently in Nix only derivations
+    # can be CA (and *all* their outputs are CA).
+    # So the next check (which assumes that if a step's output is CA then
+    # all the other outptus and the whole derivation are CA) is safe.
+    foreach my $step (@{$c->stash->{steps}}) {
+        if ($step->buildstepoutputs->search({contentaddressed => 1})->count > 0) {
+            $c->stash->{contentAddressed} = 1;
+            last;
+        }
+    }
+
     $c->stash->{binaryCachePublicUri} = $c->config->{binary_cache_public_uri};
 }
 
diff --git a/src/lib/Hydra/Schema/Result/BuildStepOutputs.pm b/src/lib/Hydra/Schema/Result/BuildStepOutputs.pm
index 6d997a8ca..42392190f 100644
--- a/src/lib/Hydra/Schema/Result/BuildStepOutputs.pm
+++ b/src/lib/Hydra/Schema/Result/BuildStepOutputs.pm
@@ -57,6 +57,11 @@ __PACKAGE__->table("buildstepoutputs");
   data_type: 'text'
   is_nullable: 1
 
+=head2 contentaddressed
+
+  data_type: 'boolean'
+  is_nullable: 0
+
 =cut
 
 __PACKAGE__->add_columns(
@@ -68,6 +73,8 @@ __PACKAGE__->add_columns(
   { data_type => "text", is_nullable => 0 },
   "path",
   { data_type => "text", is_nullable => 1 },
+  "contentaddressed",
+  { data_type => "boolean", is_nullable => 0 },
 );
 
 =head1 PRIMARY KEY
diff --git a/src/root/build.tt b/src/root/build.tt
index 93a02e0f7..79b0a1e6e 100644
--- a/src/root/build.tt
+++ b/src/root/build.tt
@@ -20,8 +20,13 @@ END;
 %]
 
 [% BLOCK renderOutputs %]
-  [% start=1; FOREACH output IN outputs %]
-    [% IF !start %],<br/>[% END; start=0; output.path %]
+  [% start=1; FOREACH output IN step.buildstepoutputs %]
+    [% IF !start %],<br/>[% END; start=0; %]
+    [% IF step.status != 0 && output.contentaddressed %]
+      [% output.name %]
+    [% ELSE %]
+      [% output.path %]
+    [% END %]
   [% END %]
 [% END %]
 
@@ -40,9 +45,9 @@ END;
             <td>[% step.stepnr %]</td>
             <td>
               [% IF step.type == 0 %]
-                Build of <tt>[% INCLUDE renderOutputs outputs=step.buildstepoutputs %]</tt>
+                Build of <tt>[% INCLUDE renderOutputs step=step %]</tt>
               [% ELSE %]
-                Substitution of <tt>[% INCLUDE renderOutputs outputs=step.buildstepoutputs %]</tt>
+                Substitution of <tt>[% INCLUDE renderOutputs step=step %]</tt>
               [% END %]
             </td>
             <td>
@@ -382,9 +387,21 @@ END;
         <td><tt>[% build.drvpath %]</tt></td>
       </tr>
       <tr>
-        <th>Output store paths:</th>
-        <td><tt>[% INCLUDE renderOutputs outputs=build.buildoutputs %]</tt></td>
+        <th>Content addressed:</th>
+        <td><tt>
+        [% IF contentAddressed %]
+          Yes
+        [% ELSE %]
+          No
+        [% END %]
+        </tt></td>
       </tr>
+        [% IF !contentAddressed || step.status == 0 %]
+        <tr>
+          <th>Output store paths:</th>
+          <td><tt>[% INCLUDE renderOutputs step=step %]</tt></td>
+        </tr>
+        [% END %]
       [% chartsURL = c.uri_for('/job' build.project.name build.jobset.name build.job) _ "#tabs-charts" %]
       [% IF build.finished && build.closuresize %]
         <tr>
diff --git a/src/sql/hydra.sql b/src/sql/hydra.sql
index e94579720..02159fe8e 100644
--- a/src/sql/hydra.sql
+++ b/src/sql/hydra.sql
@@ -300,13 +300,14 @@ create table BuildSteps (
 
 
 create table BuildStepOutputs (
-    build         integer not null,
-    stepnr        integer not null,
-    name          text not null,
-    path          text,
-    primary key   (build, stepnr, name),
-    foreign key   (build) references Builds(id) on delete cascade,
-    foreign key   (build, stepnr) references BuildSteps(build, stepnr) on delete cascade
+    build               integer not null,
+    stepnr              integer not null,
+    name                text not null,
+    path                text,
+    contentAddressed    boolean not null,
+    primary key         (build, stepnr, name),
+    foreign key         (build) references Builds(id) on delete cascade,
+    foreign key         (build, stepnr) references BuildSteps(build, stepnr) on delete cascade
 );