diff --git a/src/applications/harbormaster/query/HarbormasterBuildArtifactQuery.php b/src/applications/harbormaster/query/HarbormasterBuildArtifactQuery.php
--- a/src/applications/harbormaster/query/HarbormasterBuildArtifactQuery.php
+++ b/src/applications/harbormaster/query/HarbormasterBuildArtifactQuery.php
@@ -8,6 +8,7 @@
   private $artifactTypes;
   private $artifactKeys;
   private $keyBuildPHID;
+  private $keyBuildGeneration;
 
   public function withIDs(array $ids) {
     $this->ids = $ids;
@@ -24,8 +25,12 @@
     return $this;
   }
 
-  public function withArtifactKeys($build_phid, array $artifact_keys) {
+  public function withArtifactKeys(
+    $build_phid,
+    $build_gen,
+    array $artifact_keys) {
     $this->keyBuildPHID = $build_phid;
+    $this->keyBuildGeneration = $build_gen;
     $this->artifactKeys = $artifact_keys;
     return $this;
   }
@@ -98,7 +103,7 @@
       $indexes = array();
       foreach ($this->artifactKeys as $key) {
         $indexes[] = PhabricatorHash::digestForIndex(
-          $this->keyBuildPHID.$key);
+          $this->keyBuildPHID.$this->keyBuildGeneration.$key);
       }
 
       $where[] = qsprintf(
diff --git a/src/applications/harbormaster/storage/build/HarbormasterBuild.php b/src/applications/harbormaster/storage/build/HarbormasterBuild.php
--- a/src/applications/harbormaster/storage/build/HarbormasterBuild.php
+++ b/src/applications/harbormaster/storage/build/HarbormasterBuild.php
@@ -213,7 +213,10 @@
 
     $artifact =
       HarbormasterBuildArtifact::initializeNewBuildArtifact($build_target);
-    $artifact->setArtifactKey($this->getPHID(), $artifact_key);
+    $artifact->setArtifactKey(
+      $this->getPHID(),
+      $this->getBuildGeneration(),
+      $artifact_key);
     $artifact->setArtifactType($artifact_type);
     $artifact->save();
     return $artifact;
@@ -224,6 +227,7 @@
       ->setViewer(PhabricatorUser::getOmnipotentUser())
       ->withArtifactKeys(
         $this->getPHID(),
+        $this->getBuildGeneration(),
         array($name))
       ->executeOne();
     if ($artifact === null) {
diff --git a/src/applications/harbormaster/storage/build/HarbormasterBuildArtifact.php b/src/applications/harbormaster/storage/build/HarbormasterBuildArtifact.php
--- a/src/applications/harbormaster/storage/build/HarbormasterBuildArtifact.php
+++ b/src/applications/harbormaster/storage/build/HarbormasterBuildArtifact.php
@@ -38,9 +38,9 @@
     return $this->assertAttached($this->buildTarget);
   }
 
-  public function setArtifactKey($build_phid, $key) {
+  public function setArtifactKey($build_phid, $build_gen, $key) {
     $this->artifactIndex =
-      PhabricatorHash::digestForIndex($build_phid.$key);
+      PhabricatorHash::digestForIndex($build_phid.$build_gen.$key);
     $this->artifactKey = $key;
     return $this;
   }