diff --git a/src/main/java/com/googlesource/gerrit/plugins/simplesubmitrules/config/ConfigTranslator.java b/src/main/java/com/googlesource/gerrit/plugins/simplesubmitrules/config/ConfigTranslator.java
index bea7df0..0808bb1 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/simplesubmitrules/config/ConfigTranslator.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/simplesubmitrules/config/ConfigTranslator.java
@@ -16,7 +16,6 @@
 
 import static com.google.gerrit.server.project.ProjectCache.illegalState;
 
-import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.Sets;
 import com.google.gerrit.common.Nullable;
@@ -81,7 +80,7 @@
   }
 
   static void applyCopyScoreRulesTo(
-      Set<String> copyScoreRules, Set<String> disallowedCopyScoreRules, LabelType labelType)
+      Set<String> copyScoreRules, Set<String> disallowedCopyScoreRules, LabelType.Builder labelType)
       throws BadRequestException {
     Set<String> disallowed =
         Sets.intersection(ImmutableSet.copyOf(copyScoreRules), disallowedCopyScoreRules);
@@ -150,23 +149,16 @@
                 .orElseThrow(illegalState(projectConfig.getName()));
         projectState.getLabelTypes().getLabelTypes().stream()
             .filter(l -> l.getName().equals(entry.getKey()))
-            .filter(l -> l.canOverride())
-            .forEach(l -> copiedLabelTypes.put(l.getName(), copyLabelType(l)));
+            .filter(l -> l.isCanOverride())
+            .forEach(l -> copiedLabelTypes.put(l.getName(), l));
       }
 
       String label = entry.getKey();
       LabelDefinition definition = entry.getValue();
-      LabelType labelType = projectConfig.getLabelSections().get(label);
-
-      if (labelType == null) {
+      if (projectConfig.getLabelSections().get(label) == null) {
         throw new BadRequestException(
             "The label " + label + " does not exist. You can't change its config.");
       }
-
-      if (definition.ignoreSelfApproval != null) {
-        labelType.setIgnoreSelfApproval(definition.ignoreSelfApproval);
-      }
-
       if (definition.getFunction().isPresent()) {
         Set<String> disallowedLabelFunctions =
             ImmutableSet.copyOf(
@@ -175,14 +167,25 @@
         if (disallowedLabelFunctions.contains(function.getFunctionName())) {
           throw new BadRequestException(function.getFunctionName() + " disallowed");
         }
-        labelType.setFunction(function);
       }
+      projectConfig.updateLabelType(
+          label,
+          labelType -> {
+            if (definition.ignoreSelfApproval != null) {
+              labelType.setIgnoreSelfApproval(definition.ignoreSelfApproval);
+            }
+            if (definition.getFunction().isPresent()) {
+              labelType.setFunction(definition.getFunction().get());
+            }
+          });
 
       if (definition.copyScoreRules != null) {
+        LabelType.Builder builder = projectConfig.getLabelSections().get(label).toBuilder();
         Set<String> disallowedCopyScoreRules =
             ImmutableSet.copyOf(
                 hostPluginConfig.getStringList("disallowedCopyScoreRules-" + label));
-        applyCopyScoreRulesTo(definition.copyScoreRules, disallowedCopyScoreRules, labelType);
+        applyCopyScoreRulesTo(definition.copyScoreRules, disallowedCopyScoreRules, builder);
+        projectConfig.upsertLabelType(builder.build());
       }
     }
   }
@@ -197,7 +200,7 @@
 
     labelDefinition.function = labelType.getFunction().getFunctionName();
     extractLabelCopyScoreRules(labelType, labelDefinition);
-    labelDefinition.ignoreSelfApproval = labelType.ignoreSelfApproval();
+    labelDefinition.ignoreSelfApproval = labelType.isIgnoreSelfApproval();
   }
 
   private static void applyCommentRulesTo(@Nullable CommentsRules comments, PluginConfig config) {
@@ -208,23 +211,4 @@
         SimpleSubmitRulesConfig.KEY_BLOCK_IF_UNRESOLVED_COMMENTS,
         comments.blockIfUnresolvedComments);
   }
-
-  private static LabelType copyLabelType(LabelType label) {
-    // TODO(hiesel) Move this to core
-    LabelType copy = new LabelType(label.getName(), ImmutableList.copyOf(label.getValues()));
-    if (label.getRefPatterns() != null) {
-      copy.setRefPatterns(ImmutableList.copyOf(label.getRefPatterns()));
-    }
-    copy.setAllowPostSubmit(label.allowPostSubmit());
-    copy.setCanOverride(label.canOverride());
-    copy.setCopyAllScoresIfNoChange(label.isCopyAllScoresIfNoChange());
-    copy.setCopyAllScoresIfNoCodeChange(label.isCopyAllScoresIfNoCodeChange());
-    copy.setCopyAllScoresOnMergeFirstParentUpdate(label.isCopyAllScoresOnMergeFirstParentUpdate());
-    copy.setCopyAllScoresOnTrivialRebase(label.isCopyAllScoresOnTrivialRebase());
-    copy.setIgnoreSelfApproval(label.ignoreSelfApproval());
-    copy.setCopyMaxScore(label.isCopyMaxScore());
-    copy.setCopyMinScore(label.isCopyMinScore());
-    copy.setFunction(label.getFunction());
-    return copy;
-  }
 }
diff --git a/src/test/java/com/googlesource/gerrit/plugins/simplesubmitrules/PluginIT.java b/src/test/java/com/googlesource/gerrit/plugins/simplesubmitrules/PluginIT.java
index b0d8be2..91276af 100644
--- a/src/test/java/com/googlesource/gerrit/plugins/simplesubmitrules/PluginIT.java
+++ b/src/test/java/com/googlesource/gerrit/plugins/simplesubmitrules/PluginIT.java
@@ -140,7 +140,11 @@
 
     // Check that the label has the same configs besides the function, which we changed
     LabelType allProjectsCR = projectCache.getAllProjects().getLabelTypes().byLabel("Code-Review");
-    localCR.setFunction(allProjectsCR.getFunction());
+    projectCache
+        .get(project)
+        .get()
+        .getConfig()
+        .updateLabelType("Code-Review", lt -> lt.setFunction(allProjectsCR.getFunction()));
     assertLabelTypeEquals(localCR, allProjectsCR);
   }
 
@@ -167,15 +171,15 @@
   }
 
   private static void assertLabelTypeEquals(LabelType l1, LabelType l2) {
-    assertThat(l1.allowPostSubmit()).isEqualTo(l2.allowPostSubmit());
-    assertThat(l1.canOverride()).isEqualTo(l2.canOverride());
+    assertThat(l1.isAllowPostSubmit()).isEqualTo(l2.isAllowPostSubmit());
+    assertThat(l1.isCanOverride()).isEqualTo(l2.isCanOverride());
     assertThat(l1.getDefaultValue()).isEqualTo(l2.getDefaultValue());
     assertThat(l1.getLabelId()).isEqualTo(l2.getLabelId());
     assertThat(l1.getMax()).isEqualTo(l2.getMax());
     assertThat(l1.getMin()).isEqualTo(l2.getMin());
     assertThat(l1.getName()).isEqualTo(l2.getName());
     assertThat(l1.getRefPatterns()).isEqualTo(l2.getRefPatterns());
-    assertThat(l1.ignoreSelfApproval()).isEqualTo(l2.ignoreSelfApproval());
+    assertThat(l1.isIgnoreSelfApproval()).isEqualTo(l2.isIgnoreSelfApproval());
     assertThat(l1.isCopyAllScoresIfNoChange()).isEqualTo(l2.isCopyAllScoresIfNoChange());
     assertThat(l1.isCopyAllScoresIfNoCodeChange()).isEqualTo(l2.isCopyAllScoresIfNoCodeChange());
     assertThat(l1.isCopyAllScoresOnMergeFirstParentUpdate())
diff --git a/src/test/java/com/googlesource/gerrit/plugins/simplesubmitrules/config/ConfigTranslatorTest.java b/src/test/java/com/googlesource/gerrit/plugins/simplesubmitrules/config/ConfigTranslatorTest.java
index 05b7bf0..a7c8f18 100644
--- a/src/test/java/com/googlesource/gerrit/plugins/simplesubmitrules/config/ConfigTranslatorTest.java
+++ b/src/test/java/com/googlesource/gerrit/plugins/simplesubmitrules/config/ConfigTranslatorTest.java
@@ -29,28 +29,28 @@
 public class ConfigTranslatorTest {
   @Test
   public void checkLabelTranslation() throws Exception {
-    checkTranslation("copyMinScore", LabelType::isCopyMinScore, LabelType::setCopyMinScore);
-    checkTranslation("copyMaxScore", LabelType::isCopyMaxScore, LabelType::setCopyMaxScore);
+    checkTranslation("copyMinScore", LabelType::isCopyMinScore, LabelType.Builder::setCopyMinScore);
+    checkTranslation("copyMaxScore", LabelType::isCopyMaxScore, LabelType.Builder::setCopyMaxScore);
 
     checkTranslation(
         "copyAllScoresIfNoChange",
         LabelType::isCopyAllScoresIfNoChange,
-        LabelType::setCopyAllScoresIfNoChange);
+        LabelType.Builder::setCopyAllScoresIfNoChange);
 
     checkTranslation(
         "copyAllScoresIfNoCodeChange",
         LabelType::isCopyAllScoresIfNoCodeChange,
-        LabelType::setCopyAllScoresIfNoCodeChange);
+        LabelType.Builder::setCopyAllScoresIfNoCodeChange);
 
     checkTranslation(
         "copyAllScoresOnMergeFirstParentUpdate",
         LabelType::isCopyAllScoresOnMergeFirstParentUpdate,
-        LabelType::setCopyAllScoresOnMergeFirstParentUpdate);
+        LabelType.Builder::setCopyAllScoresOnMergeFirstParentUpdate);
 
     checkTranslation(
         "copyAllScoresOnTrivialRebase",
         LabelType::isCopyAllScoresOnTrivialRebase,
-        LabelType::setCopyAllScoresOnTrivialRebase);
+        LabelType.Builder::setCopyAllScoresOnTrivialRebase);
   }
 
   @Test
@@ -63,7 +63,7 @@
                     ImmutableSet.of(
                         "copyAllScoresIfNoChange", "copyAllScoresOnMergeFirstParentUpdate"),
                     ImmutableSet.of("copyAllScoresIfNoChange"),
-                    LabelType.withDefaultValues("Verified")));
+                    LabelType.withDefaultValues("Verified").toBuilder()));
     assertThat(thrown)
         .hasMessageThat()
         .contains("copy score rules [copyAllScoresIfNoChange] are forbidden");
@@ -73,7 +73,7 @@
   private static void checkTranslation(
       String copyScoreName,
       Predicate<LabelType> functionToCheck,
-      BiConsumer<LabelType, Boolean> functionToSet)
+      BiConsumer<LabelType.Builder, Boolean> functionToSet)
       throws Exception {
     checkLabelToGerritPresent(copyScoreName, functionToCheck);
     checkLabelToGerritAbsent(copyScoreName, functionToCheck);
@@ -83,13 +83,13 @@
   }
 
   private static void checkLabelFromGerritPresent(
-      String copyScoreName, BiConsumer<LabelType, Boolean> functionToSet) {
+      String copyScoreName, BiConsumer<LabelType.Builder, Boolean> functionToSet) {
 
-    LabelType label = LabelType.withDefaultValues("Verified");
+    LabelType.Builder label = LabelType.withDefaultValues("Verified").toBuilder();
     LabelDefinition labelDefinition = new LabelDefinition();
 
     functionToSet.accept(label, false);
-    ConfigTranslator.extractLabelCopyScoreRules(label, labelDefinition);
+    ConfigTranslator.extractLabelCopyScoreRules(label.build(), labelDefinition);
 
     assertWithMessage("[case %s:false]", copyScoreName)
         .that(labelDefinition.copyScoreRules)
@@ -97,13 +97,13 @@
   }
 
   private static void checkLabelFromGerritAbsent(
-      String copyScoreName, BiConsumer<LabelType, Boolean> functionToSet) {
+      String copyScoreName, BiConsumer<LabelType.Builder, Boolean> functionToSet) {
 
-    LabelType label = LabelType.withDefaultValues("Verified");
+    LabelType.Builder label = LabelType.withDefaultValues("Verified").toBuilder();
     LabelDefinition labelDefinition = new LabelDefinition();
 
     functionToSet.accept(label, true);
-    ConfigTranslator.extractLabelCopyScoreRules(label, labelDefinition);
+    ConfigTranslator.extractLabelCopyScoreRules(label.build(), labelDefinition);
 
     assertWithMessage("[case %s:true]", copyScoreName)
         .that(labelDefinition.copyScoreRules)
@@ -112,18 +112,21 @@
 
   private static void checkLabelToGerritPresent(
       String copyScoreName, Predicate<LabelType> functionToCheck) throws Exception {
-    LabelType label = LabelType.withDefaultValues("Verified");
-
+    LabelType.Builder label = LabelType.withDefaultValues("Verified").toBuilder();
     ConfigTranslator.applyCopyScoreRulesTo(
         ImmutableSet.of(copyScoreName), ImmutableSet.of(), label);
-    assertWithMessage("[case %s:true]", copyScoreName).that(functionToCheck.test(label)).isTrue();
+    assertWithMessage("[case %s:true]", copyScoreName)
+        .that(functionToCheck.test(label.build()))
+        .isTrue();
   }
 
   private static void checkLabelToGerritAbsent(
       String copyScoreName, Predicate<LabelType> functionToCheck) throws Exception {
-    LabelType label = LabelType.withDefaultValues("Verified");
+    LabelType.Builder label = LabelType.withDefaultValues("Verified").toBuilder();
 
     ConfigTranslator.applyCopyScoreRulesTo(ImmutableSet.of(), ImmutableSet.of(), label);
-    assertWithMessage("[case %s:false]", copyScoreName).that(functionToCheck.test(label)).isFalse();
+    assertWithMessage("[case %s:false]", copyScoreName)
+        .that(functionToCheck.test(label.build()))
+        .isFalse();
   }
 }