diff --git a/src/main/java/com/spotify/reaper/core/Cluster.java b/src/main/java/com/spotify/reaper/core/Cluster.java
index 3d54979ee..b27b99e20 100644
--- a/src/main/java/com/spotify/reaper/core/Cluster.java
+++ b/src/main/java/com/spotify/reaper/core/Cluster.java
@@ -28,21 +28,18 @@ private Cluster(Builder builder) {
 
   public static class Builder {
 
-    private final String name;
-    private String partitioner;
-    private Set<String> seedHosts;
+    public final String name;
+    public final String partitioner;
+    private final Set<String> seedHosts;
 
-    public Builder(String name) {
+    public Builder(String name, String partitioner, Set<String> seedHosts) {
       this.name = name;
-    }
-
-    public Builder partitioner(String partitioner) {
       this.partitioner = partitioner;
-      return this;
+      this.seedHosts = seedHosts;
     }
 
-    public Builder seedHosts(Set<String> seedHosts) {
-      this.seedHosts = seedHosts;
+    public Builder addSeedHost(String seedHost) {
+      seedHosts.add(seedHost);
       return this;
     }
 
diff --git a/src/main/java/com/spotify/reaper/core/ColumnFamily.java b/src/main/java/com/spotify/reaper/core/ColumnFamily.java
index 87fd78ec6..81cf7732c 100644
--- a/src/main/java/com/spotify/reaper/core/ColumnFamily.java
+++ b/src/main/java/com/spotify/reaper/core/ColumnFamily.java
@@ -2,22 +2,17 @@
 
 public class ColumnFamily {
 
-  private Long id;
+  private final long id;
   private final Cluster cluster;
   private final String keyspaceName;
   private final String name;
   private final int segmentCount; // int/long/BigInteger?
   private final boolean snapshotRepair;
 
-  public Long getId() {
+  public long getId() {
     return id;
   }
 
-  public void setId(long id) {
-    assert this.id == null : "cannot reset id after once set";
-    this.id = id;
-  }
-
   public Cluster getCluster() {
     return cluster;
   }
@@ -38,8 +33,8 @@ public boolean isSnapshotRepair() {
     return snapshotRepair;
   }
 
-  private ColumnFamily(Builder builder) {
-    this.id = builder.id;
+  private ColumnFamily(Builder builder, long id) {
+    this.id = id;
     this.cluster = builder.cluster;
     this.keyspaceName = builder.keyspaceName;
     this.name = builder.name;
@@ -50,46 +45,23 @@ private ColumnFamily(Builder builder) {
 
   public static class Builder {
 
-    private Long id;
-    private Cluster cluster;
-    private String keyspaceName;
-    private String name;
-    private int segmentCount;
-    private boolean snapshotRepair;
+    public final Cluster cluster;
+    public final String keyspaceName;
+    public final String name;
+    public final int segmentCount;
+    public final boolean snapshotRepair;
 
-    public Builder id(long id) {
-      this.id = id;
-      return this;
-    }
-
-    public Builder cluster(Cluster cluster) {
+    public Builder(Cluster cluster, String keyspaceName, String name, int segmentCount,
+                   boolean snapshotRepair) {
       this.cluster = cluster;
-      return this;
-    }
-
-    public Builder keyspaceName(String keyspaceName) {
       this.keyspaceName = keyspaceName;
-      return this;
-    }
-
-    public Builder name(String name) {
       this.name = name;
-      return this;
-    }
-
-    public Builder segmentCount(int segmentCount) {
       this.segmentCount = segmentCount;
-      return this;
-    }
-
-    public Builder snapshotRepair(boolean snapshotRepair) {
       this.snapshotRepair = snapshotRepair;
-      return this;
     }
 
-
-    public ColumnFamily build() {
-      return new ColumnFamily(this);
+    public ColumnFamily build(long id) {
+      return new ColumnFamily(this, id);
     }
   }
 }
diff --git a/src/main/java/com/spotify/reaper/core/RepairRun.java b/src/main/java/com/spotify/reaper/core/RepairRun.java
index 95e4cabcf..3fe50f786 100644
--- a/src/main/java/com/spotify/reaper/core/RepairRun.java
+++ b/src/main/java/com/spotify/reaper/core/RepairRun.java
@@ -4,7 +4,7 @@
 
 public class RepairRun {
 
-  private Long id;
+  private final long id;
 
   // IDEA: maybe we want to have start and stop token for parallel runners on same repair run?
   //private final long startToken;
@@ -18,15 +18,10 @@ public class RepairRun {
   private final DateTime endTime;
   private final double intensity;
 
-  public Long getId() {
+  public long getId() {
     return id;
   }
 
-  public void setId(long id) {
-    assert this.id == null : "cannot reset id after once set";
-    this.id = id;
-  }
-
   public String getCause() {
     return cause;
   }
@@ -62,8 +57,8 @@ public enum State {
     PAUSED
   }
 
-  private RepairRun(Builder builder) {
-    this.id = builder.id;
+  private RepairRun(Builder builder, long id) {
+    this.id = id;
     this.cause = builder.cause;
     this.owner = builder.owner;
     this.state = builder.state;
@@ -75,18 +70,18 @@ private RepairRun(Builder builder) {
 
   public static class Builder {
 
-    private Long id;
+    public final State state;
+    public final DateTime creationTime;
+    public final double intensity;
     private String cause;
     private String owner;
-    private State state;
-    private DateTime creationTime;
     private DateTime startTime;
     private DateTime endTime;
-    private double intensity;
 
-    public Builder id(long id) {
-      this.id = id;
-      return this;
+    public Builder(State state, DateTime creationTime, double intensity) {
+      this.state = state;
+      this.creationTime = creationTime;
+      this.intensity = intensity;
     }
 
     public Builder cause(String cause) {
@@ -99,16 +94,6 @@ public Builder owner(String owner) {
       return this;
     }
 
-    public Builder state(State state) {
-      this.state = state;
-      return this;
-    }
-
-    public Builder creationTime(DateTime creationTime) {
-      this.creationTime = creationTime;
-      return this;
-    }
-
     public Builder startTime(DateTime startTime) {
       this.startTime = startTime;
       return this;
@@ -119,13 +104,8 @@ public Builder endTime(DateTime endTime) {
       return this;
     }
 
-    public Builder intensity(double intensity) {
-      this.intensity = intensity;
-      return this;
-    }
-
-    public RepairRun build() {
-      return new RepairRun(this);
+    public RepairRun build(long id) {
+      return new RepairRun(this, id);
     }
   }
 }
diff --git a/src/main/java/com/spotify/reaper/core/RepairSegment.java b/src/main/java/com/spotify/reaper/core/RepairSegment.java
index ec99dc628..dce6fc9c8 100644
--- a/src/main/java/com/spotify/reaper/core/RepairSegment.java
+++ b/src/main/java/com/spotify/reaper/core/RepairSegment.java
@@ -6,7 +6,7 @@
 
 public class RepairSegment {
 
-  private Long id;
+  private final long id;
   private final ColumnFamily columnFamily;
   private final long runID;
   private final BigInteger startToken; // open/exclusive
@@ -15,15 +15,10 @@ public class RepairSegment {
   private final DateTime startTime;
   private final DateTime endTime;
 
-  public Long getId() {
+  public long getId() {
     return id;
   }
 
-  public void setId(long id) {
-    assert this.id == null : "cannot reset id after once set";
-    this.id = id;
-  }
-
   public ColumnFamily getColumnFamily() {
     return columnFamily;
   }
@@ -58,8 +53,8 @@ public enum State {
     DONE
   }
 
-  private RepairSegment(Builder builder) {
-    this.id = builder.id;
+  private RepairSegment(Builder builder, long id) {
+    this.id = id;
     this.columnFamily = builder.columnFamily;
     this.runID = builder.runID;
     this.startToken = builder.startToken;
@@ -71,43 +66,20 @@ private RepairSegment(Builder builder) {
 
   public static class Builder {
 
-    private Long id;
-    private ColumnFamily columnFamily;
-    private long runID;
-    private BigInteger startToken;
-    private BigInteger endToken;
-    private RepairSegment.State state;
+    public final ColumnFamily columnFamily;
+    public final long runID;
+    public final BigInteger startToken;
+    public final BigInteger endToken;
+    public final State state;
     private DateTime startTime;
     private DateTime endTime;
 
-    public Builder id(long id) {
-      this.id = id;
-      return this;
-    }
-
-    public Builder columnFamily(ColumnFamily columnFamily) {
+    public Builder(ColumnFamily columnFamily, long runID, BigInteger startToken, BigInteger endToken, State state) {
       this.columnFamily = columnFamily;
-      return this;
-    }
-
-    public Builder runID(long runID) {
       this.runID = runID;
-      return this;
-    }
-
-    public Builder startToken(BigInteger startToken) {
       this.startToken = startToken;
-      return this;
-    }
-
-    public Builder endToken(BigInteger endToken) {
-      this.endToken = endToken;
-      return this;
-    }
-
-    public Builder state(RepairSegment.State state) {
+      this. endToken = endToken;
       this.state = state;
-      return this;
     }
 
     public Builder startTime(DateTime startTime) {
@@ -120,14 +92,13 @@ public Builder endTime(DateTime endTime) {
       return this;
     }
 
-
-    public RepairSegment build() {
-      return new RepairSegment(this);
+    public RepairSegment build(long id) {
+      return new RepairSegment(this, id);
     }
-  }
 
-  @Override
-  public String toString() {
-    return String.format("(%s,%s]", startToken.toString(), endToken.toString());
+    @Override
+    public String toString() {
+      return String.format("(%s,%s]", startToken.toString(), endToken.toString());
+    }
   }
 }
diff --git a/src/main/java/com/spotify/reaper/resources/ClusterResource.java b/src/main/java/com/spotify/reaper/resources/ClusterResource.java
index 3fe440533..5be3423c5 100644
--- a/src/main/java/com/spotify/reaper/resources/ClusterResource.java
+++ b/src/main/java/com/spotify/reaper/resources/ClusterResource.java
@@ -99,9 +99,9 @@ public static Cluster createClusterWithSeedHost(String seedHost)
       e.printStackTrace();
       throw e;
     }
-    Cluster newCluster = new Cluster.Builder(clusterName)
-        .seedHosts(Collections.singleton(seedHost))
-        .partitioner(partitioner).build();
+    Cluster newCluster =
+        new Cluster.Builder(clusterName, partitioner, Collections.singleton(seedHost))
+            .build();
     return newCluster;
   }
 
diff --git a/src/main/java/com/spotify/reaper/resources/TableResource.java b/src/main/java/com/spotify/reaper/resources/TableResource.java
index e5be47eb6..308801028 100644
--- a/src/main/java/com/spotify/reaper/resources/TableResource.java
+++ b/src/main/java/com/spotify/reaper/resources/TableResource.java
@@ -115,18 +115,13 @@ public Response addTable(@Context UriInfo uriInfo,
     }
 
     // TODO: verify that the table exists in the cluster.
-    ColumnFamily newTable = new ColumnFamily.Builder()
-        .cluster(targetCluster)
-        .keyspaceName(keyspace.get())
-        .name(table.get())
-        .keyspaceName(keyspace.get())
-        .snapshotRepair(config.getSnapshotRepair())
-        .segmentCount(config.getSegmentCount())
-        .build();
+    ColumnFamily newTable = storage.addColumnFamily(
+        new ColumnFamily.Builder(targetCluster, keyspace.get(), table.get(),
+                                 config.getSegmentCount(), config.getSnapshotRepair()));
 
     String newTablePathPart = newTable.getCluster().getName() + "/" + newTable.getKeyspaceName()
                               + "/" + newTable.getName();
-    if (!storage.addColumnFamily(newTable)) {
+    if (newTable == null) {
       return Response.status(500)
           .entity("failed creating table into Reaper storage: " + newTablePathPart).build();
     }
@@ -144,21 +139,19 @@ public Response addTable(@Context UriInfo uriInfo,
     // Start repairing the table if the startRepair query parameter is given at all,
     // i.e. possible value not checked, and not required.
     if (startRepair.isPresent()) {
-      RepairRun newRepairRun = new RepairRun.Builder()
-          .cause(cause.isPresent() ? cause.get() : "no cause specified")
-          .owner(owner.get())
-          .intensity(config.getRepairIntensity())
-          .state(RepairRun.State.NOT_STARTED)
-          .creationTime(DateTime.now())
-          .build();
-      if (!storage.addRepairRun(newRepairRun)) {
+      RepairRun newRepairRun =
+          storage.addRepairRun(new RepairRun.Builder(RepairRun.State.NOT_STARTED, DateTime.now(),
+                                                     config.getRepairIntensity())
+                                   .cause(cause.isPresent() ? cause.get() : "no cause specified")
+                                   .owner(owner.get()));
+      if (newRepairRun == null) {
         return Response.status(500)
             .entity("failed creating repair run into Reaper storage for owner: " + owner.get())
             .build();
       }
 
       // create segments
-      List<RepairSegment> segments = null;
+      List<RepairSegment.Builder> segments = null;
       try {
         SegmentGenerator sg = new SegmentGenerator(targetCluster.getPartitioner());
         Set<String> seedHosts = targetCluster.getSeedHosts();
diff --git a/src/main/java/com/spotify/reaper/service/SegmentGenerator.java b/src/main/java/com/spotify/reaper/service/SegmentGenerator.java
index 560129fc4..dec0bbbb8 100644
--- a/src/main/java/com/spotify/reaper/service/SegmentGenerator.java
+++ b/src/main/java/com/spotify/reaper/service/SegmentGenerator.java
@@ -48,12 +48,13 @@ public SegmentGenerator(String partitioner) throws ReaperException {
    * @param ringTokens        list of all start tokens in a cluster. They have to be in ring order.
    * @return a list containing at least {@code totalSegmentCount} repair segments.
    */
-  public List<RepairSegment> generateSegments(int totalSegmentCount, List<BigInteger> ringTokens,
-                                              long runId, ColumnFamily table)
+  public List<RepairSegment.Builder> generateSegments(int totalSegmentCount,
+                                                      List<BigInteger> ringTokens,
+                                                      long runId, ColumnFamily table)
       throws ReaperException {
     int tokenRangeCount = ringTokens.size();
 
-    List<RepairSegment> repairSegments = Lists.newArrayList();
+    List<RepairSegment.Builder> repairSegments = Lists.newArrayList();
     for (int i = 0; i < tokenRangeCount; i++) {
       BigInteger start = ringTokens.get(i);
       BigInteger stop = ringTokens.get((i + 1) % tokenRangeCount);
@@ -97,13 +98,10 @@ public List<RepairSegment> generateSegments(int totalSegmentCount, List<BigInteg
 
       // Append the segments between the endpoints
       for (int j = 0; j < segmentCount; j++) {
-        repairSegments.add(new RepairSegment.Builder()
-                               .runID(runId)
-                               .columnFamily(table)
-                               .state(RepairSegment.State.NOT_STARTED)
-                               .startToken(endpointTokens.get(j))
-                               .endToken(endpointTokens.get(j + 1))
-                               .build());
+        repairSegments.add(new RepairSegment.Builder(table, runId,
+                                                     endpointTokens.get(j),
+                                                     endpointTokens.get(j + 1),
+                                                     RepairSegment.State.NOT_STARTED));
         LOG.debug("Segment #{}: [{},{})", j + 1, endpointTokens.get(j),
                   endpointTokens.get(j + 1));
       }
@@ -111,8 +109,8 @@ public List<RepairSegment> generateSegments(int totalSegmentCount, List<BigInteg
 
     // verify that the whole range is repaired
     BigInteger total = BigInteger.ZERO;
-    for (RepairSegment segment : repairSegments) {
-      BigInteger size = segment.getEndToken().subtract(segment.getStartToken());
+    for (RepairSegment.Builder segment : repairSegments) {
+      BigInteger size = segment.endToken.subtract(segment.startToken);
       if (lowerThan(size, BigInteger.ZERO))
         size = size.add(RANGE_SIZE);
       total = total.add(size);
diff --git a/src/main/java/com/spotify/reaper/storage/IStorage.java b/src/main/java/com/spotify/reaper/storage/IStorage.java
index 6bf7007b0..093d56e7b 100644
--- a/src/main/java/com/spotify/reaper/storage/IStorage.java
+++ b/src/main/java/com/spotify/reaper/storage/IStorage.java
@@ -12,25 +12,26 @@
  */
 public interface IStorage {
 
-  public boolean addCluster(Cluster newCluster);
+  Cluster addCluster(Cluster cluster);
 
-  public boolean updateCluster(Cluster newCluster);
+  Cluster updateCluster(Cluster newCluster);
 
-  public Cluster getCluster(String clusterName);
+  Cluster getCluster(String clusterName);
 
-  public boolean addRepairRun(RepairRun newRepairRun);
+  RepairRun addRepairRun(RepairRun.Builder repairRun);
 
-  public RepairRun getRepairRun(long id);
+  RepairRun getRepairRun(long id);
 
-  public boolean addColumnFamily(ColumnFamily newTable);
+  ColumnFamily addColumnFamily(ColumnFamily.Builder newTable);
 
-  public ColumnFamily getColumnFamily(long id);
+  ColumnFamily getColumnFamily(long id);
+  ColumnFamily getColumnFamily(String cluster, String keyspace, String table);
 
-  public boolean addRepairSegments(Collection<RepairSegment> newSegments);
+  boolean addRepairSegments(Collection<RepairSegment> newSegments);
 
-  public boolean updateRepairSegment(RepairSegment newRepairSegment);
+  boolean updateRepairSegment(RepairSegment newRepairSegment);
 
-  public RepairSegment getNextFreeSegment(long runId);
+  RepairSegment getNextFreeSegment(long runId);
 
-  public RepairSegment getNextFreeSegmentInRange(long runId, long start, long end);
+  RepairSegment getNextFreeSegmentInRange(long runId, long start, long end);
 }
diff --git a/src/main/java/com/spotify/reaper/storage/MemoryStorage.java b/src/main/java/com/spotify/reaper/storage/MemoryStorage.java
index 1cf9185e2..0624e402f 100644
--- a/src/main/java/com/spotify/reaper/storage/MemoryStorage.java
+++ b/src/main/java/com/spotify/reaper/storage/MemoryStorage.java
@@ -22,16 +22,47 @@ public class MemoryStorage implements IStorage {
   private Map<String, Cluster> clusters = Maps.newHashMap();
   private Map<Long, RepairRun> repairRuns = Maps.newHashMap();
   private Map<Long, ColumnFamily> columnFamilies = Maps.newHashMap();
+  private Map<TableName, ColumnFamily> columnFamiliesByName = Maps.newHashMap();
+
+  public static class TableName {
+    public final String cluster;
+    public final String keyspace;
+    public final String table;
+
+    public TableName(String cluster, String keyspace, String table) {
+      this.cluster = cluster;
+      this.keyspace = keyspace;
+      this.table = table;
+    }
+
+    @Override
+    public boolean equals(Object other) {
+      if (other instanceof TableName) {
+        return
+            cluster.equals(((TableName) other).cluster) &&
+            keyspace.equals(((TableName) other).keyspace) &&
+            table.equals(((TableName) other).table);
+      } else {
+        return false;
+      }
+    }
+
+    @Override
+    public int hashCode() {
+      return (cluster + keyspace + table).hashCode();
+    }
+  }
 
   @Override
-  public boolean addCluster(Cluster cluster) {
-    clusters.put(cluster.getName(), cluster);
-    return true;
+  public Cluster addCluster(Cluster cluster) {
+    Cluster existing = clusters.putIfAbsent(cluster.getName(), cluster);
+    return existing == null ? cluster : null;
   }
 
   @Override
-  public boolean updateCluster(Cluster cluster) {
-    return addCluster(cluster);
+  public Cluster updateCluster(Cluster newCluster) {
+    clusters.put(newCluster.getName(), newCluster);
+    return newCluster;
   }
 
   @Override
@@ -40,11 +71,10 @@ public Cluster getCluster(String clusterName) {
   }
 
   @Override
-  public boolean addRepairRun(RepairRun newRepairRun) {
-    assert newRepairRun.getId() == null : "new RepairRun instance must NOT have ID set";
-    newRepairRun.setId(REPAIR_RUN_ID.incrementAndGet());
+  public RepairRun addRepairRun(RepairRun.Builder repairRun) {
+    RepairRun newRepairRun = repairRun.build(REPAIR_RUN_ID.incrementAndGet());
     repairRuns.put(newRepairRun.getId(), newRepairRun);
-    return true;
+    return newRepairRun;
   }
 
   @Override
@@ -53,11 +83,22 @@ public RepairRun getRepairRun(long id) {
   }
 
   @Override
-  public boolean addColumnFamily(ColumnFamily newColumnFamily) {
-    assert newColumnFamily.getId() == null : "new ColumnFamily instance must NOT have ID set";
-    newColumnFamily.setId(COLUMN_FAMILY_ID.incrementAndGet());
-    columnFamilies.put(newColumnFamily.getId(), newColumnFamily);
-    return true;
+  public ColumnFamily addColumnFamily(ColumnFamily.Builder columnFamily) {
+    ColumnFamily
+        existing =
+        getColumnFamily(columnFamily.cluster.getName(), columnFamily.keyspaceName,
+                        columnFamily.name);
+    if (existing == null) {
+      ColumnFamily newColumnFamily = columnFamily.build(COLUMN_FAMILY_ID.incrementAndGet());
+      columnFamilies.put(newColumnFamily.getId(), newColumnFamily);
+      columnFamiliesByName
+          .put(new TableName(newColumnFamily.getCluster().getName(),
+                             newColumnFamily.getKeyspaceName(),
+                             newColumnFamily.getName()), newColumnFamily);
+      return newColumnFamily;
+    } else {
+      return null;
+    }
   }
 
   @Override
@@ -65,6 +106,11 @@ public ColumnFamily getColumnFamily(long id) {
     return columnFamilies.get(id);
   }
 
+  @Override
+  public ColumnFamily getColumnFamily(String cluster, String keyspace, String table) {
+    return columnFamiliesByName.get(new TableName(cluster, keyspace, table));
+  }
+
   @Override
   public boolean addRepairSegments(Collection<RepairSegment> newSegments) {
     // TODO:
diff --git a/src/main/java/com/spotify/reaper/storage/PostgresStorage.java b/src/main/java/com/spotify/reaper/storage/PostgresStorage.java
index d43857cb7..81fb31269 100644
--- a/src/main/java/com/spotify/reaper/storage/PostgresStorage.java
+++ b/src/main/java/com/spotify/reaper/storage/PostgresStorage.java
@@ -49,35 +49,35 @@ public Cluster getCluster(String clusterName) {
   }
 
   @Override
-  public boolean addRepairRun(RepairRun newRepairRun) {
+  public RepairRun addRepairRun(RepairRun.Builder newRepairRun) {
     // TODO: implementation
-    return false;
+    return null;
   }
 
   @Override
-  public boolean addCluster(Cluster newCluster) {
+  public Cluster addCluster(Cluster newCluster) {
     Handle h = jdbi.open();
     IStoragePostgreSQL postgres = h.attach(IStoragePostgreSQL.class);
     int rowsAdded = postgres.insertCluster(newCluster);
     h.close();
     if (rowsAdded < 1) {
       LOG.warn("failed inserting cluster with name: {}", newCluster.getName());
-      return false;
+      return null;
     }
-    return true;
+    return newCluster;
   }
 
   @Override
-  public boolean updateCluster(Cluster cluster) {
+  public Cluster updateCluster(Cluster cluster) {
     Handle h = jdbi.open();
     IStoragePostgreSQL postgres = h.attach(IStoragePostgreSQL.class);
     int rowsAdded = postgres.updateCluster(cluster);
     h.close();
     if (rowsAdded < 1) {
       LOG.warn("failed updating cluster with name: {}", cluster.getName());
-      return false;
+      return null;
     }
-    return true;
+    return cluster;
   }
 
   @Override
@@ -87,9 +87,9 @@ public RepairRun getRepairRun(long id) {
   }
 
   @Override
-  public boolean addColumnFamily(ColumnFamily newTable) {
+  public ColumnFamily addColumnFamily(ColumnFamily.Builder newTable) {
     // TODO: implementation
-    return false;
+    return null;
   }
 
   @Override
@@ -98,6 +98,11 @@ public ColumnFamily getColumnFamily(long id) {
     return null;
   }
 
+  @Override
+  public ColumnFamily getColumnFamily(String cluster, String keyspace, String table) {
+    return null;
+  }
+
   @Override
   public boolean addRepairSegments(Collection<RepairSegment> newSegments) {
     // TODO: implementation
diff --git a/src/main/java/com/spotify/reaper/storage/postgresql/ClusterMapper.java b/src/main/java/com/spotify/reaper/storage/postgresql/ClusterMapper.java
index 20f33fc0a..e3b04f979 100644
--- a/src/main/java/com/spotify/reaper/storage/postgresql/ClusterMapper.java
+++ b/src/main/java/com/spotify/reaper/storage/postgresql/ClusterMapper.java
@@ -1,5 +1,7 @@
 package com.spotify.reaper.storage.postgresql;
 
+import com.google.common.collect.Sets;
+
 import com.spotify.reaper.core.Cluster;
 
 import org.skife.jdbi.v2.StatementContext;
@@ -14,10 +16,8 @@ public class ClusterMapper implements ResultSetMapper<Cluster> {
 
   public Cluster map(int index, ResultSet r, StatementContext ctx) throws SQLException {
     String[] seedHosts = (String[]) r.getArray("seed_hosts").getArray();
-    return new Cluster.Builder(r.getString("name"))
-        .partitioner(r.getString("partitioner"))
-        .seedHosts(new HashSet<String>(Arrays.asList(seedHosts)))
-        .build();
+    return new Cluster.Builder(r.getString("name"), r.getString("partitioner"),
+                               Sets.newHashSet(Arrays.asList(seedHosts))).build();
   }
 
 }
diff --git a/src/test/java/com/spotify/reaper/service/SegmentGeneratorTest.java b/src/test/java/com/spotify/reaper/service/SegmentGeneratorTest.java
index d7362fc03..8d6f592cc 100644
--- a/src/test/java/com/spotify/reaper/service/SegmentGeneratorTest.java
+++ b/src/test/java/com/spotify/reaper/service/SegmentGeneratorTest.java
@@ -34,7 +34,7 @@ public BigInteger apply(@Nullable String s) {
     );
 
     SegmentGenerator generator = new SegmentGenerator("foo.bar.RandomPartitioner");
-    List<RepairSegment> segments = generator.generateSegments(10, tokens, -1, null);
+    List<RepairSegment.Builder> segments = generator.generateSegments(10, tokens, -1, null);
     assertEquals(15, segments.size());
     assertEquals("(0,1]",
                  segments.get(0).toString());
@@ -101,7 +101,7 @@ public BigInteger apply(@Nullable String s) {
     });
 
     SegmentGenerator generator = new SegmentGenerator("foo.bar.RandomPartitioner");
-    List<RepairSegment> segments = generator.generateSegments(10, tokens, -1, null);
+    List<RepairSegment.Builder> segments = generator.generateSegments(10, tokens, -1, null);
     assertEquals(15, segments.size());
     assertEquals("(113427455640312821154458202477256070484,113427455640312821154458202477256070485]",
                  segments.get(4).toString());