diff --git a/src/avalanche/peermanager.h b/src/avalanche/peermanager.h
--- a/src/avalanche/peermanager.h
+++ b/src/avalanche/peermanager.h
@@ -21,11 +21,18 @@
 class PeerManager {
     std::vector<Slot> slots;
     uint64_t slotCount = 0;
+    uint64_t fragmentation = 0;
 
 public:
     void addPeer(uint64_t score);
+    void rescorePeer(size_t i, uint64_t score);
+    void removePeer(size_t i) { rescorePeer(i, 0); }
 
     size_t selectPeer() const;
+
+    // Accssors.
+    uint64_t getSlotCount() const { return slotCount; }
+    uint64_t getFragmentation() const { return fragmentation; }
 };
 
 /**
diff --git a/src/avalanche/peermanager.cpp b/src/avalanche/peermanager.cpp
--- a/src/avalanche/peermanager.cpp
+++ b/src/avalanche/peermanager.cpp
@@ -13,6 +13,33 @@
     slotCount = stop;
 }
 
+void PeerManager::rescorePeer(size_t i, uint64_t score) {
+    assert(i < slots.size());
+
+    const uint64_t start = slots[i].start;
+    const uint64_t stop = start + score;
+
+    // If this is the last element, we can extend/shrink easily.
+    if (i + 1 == slots.size()) {
+        slots[i].stop = stop;
+        slotCount = stop;
+        return;
+    }
+
+    const uint64_t nextStart = slots[i + 1].start;
+
+    // We can extend in place.
+    if (stop <= nextStart) {
+        fragmentation += (slots[i].stop - stop);
+        slots[i].stop = stop;
+        return;
+    }
+
+    // So we remove and insert a new entry.
+    addPeer(score);
+    removePeer(i);
+}
+
 size_t PeerManager::selectPeer() const {
     if (slots.empty()) {
         return NO_PEER;
diff --git a/src/avalanche/test/peermanager_tests.cpp b/src/avalanche/test/peermanager_tests.cpp
--- a/src/avalanche/test/peermanager_tests.cpp
+++ b/src/avalanche/test/peermanager_tests.cpp
@@ -177,4 +177,101 @@
     BOOST_CHECK(abs(results[0] - results[1] + results[2]) < 500);
 }
 
+BOOST_AUTO_TEST_CASE(remove_peer) {
+    // No peers.
+    PeerManager pm;
+    BOOST_CHECK_EQUAL(pm.selectPeer(), NO_PEER);
+
+    // Add 4 peers.
+    for (int i = 0; i < 4; i++) {
+        pm.addPeer(100);
+    }
+
+    for (int i = 0; i < 100; i++) {
+        size_t p = pm.selectPeer();
+        BOOST_CHECK(p <= 4);
+    }
+
+    // Remove one peer, it nevers show up now.
+    pm.removePeer(3);
+    for (int i = 0; i < 100; i++) {
+        size_t p = pm.selectPeer();
+        BOOST_CHECK(p < 4);
+        BOOST_CHECK(p != 3);
+    }
+
+    // Add 4 more peers.
+    for (int i = 0; i < 4; i++) {
+        pm.addPeer(100);
+    }
+
+    pm.removePeer(0);
+    pm.removePeer(7);
+    for (int i = 0; i < 100; i++) {
+        size_t p = pm.selectPeer();
+        BOOST_CHECK(p < 8);
+        BOOST_CHECK(p != 0);
+        BOOST_CHECK(p != 3);
+        BOOST_CHECK(p != 7);
+    }
+}
+
+BOOST_AUTO_TEST_CASE(rescore_peer, *boost::unit_test::timeout(5)) {
+    // No peers.
+    PeerManager pm;
+    BOOST_CHECK_EQUAL(pm.selectPeer(), NO_PEER);
+
+    // Add 4 peers.
+    for (int i = 0; i < 4; i++) {
+        pm.addPeer(100);
+    }
+
+    BOOST_CHECK_EQUAL(pm.getSlotCount(), 400);
+    BOOST_CHECK_EQUAL(pm.getFragmentation(), 0);
+
+    for (int i = 0; i < 100; i++) {
+        size_t p = pm.selectPeer();
+        BOOST_CHECK(p <= 4);
+    }
+
+    // Set one peer's score to 0, it nevers show up now.
+    pm.rescorePeer(1, 0);
+    BOOST_CHECK_EQUAL(pm.getSlotCount(), 400);
+    BOOST_CHECK_EQUAL(pm.getFragmentation(), 100);
+
+    for (int i = 0; i < 100; i++) {
+        size_t p = pm.selectPeer();
+        BOOST_CHECK(p < 4);
+        BOOST_CHECK(p != 1);
+    }
+
+    // "resurrect" the peer.
+    pm.rescorePeer(1, 100);
+    BOOST_CHECK_EQUAL(pm.getSlotCount(), 400);
+    BOOST_CHECK_EQUAL(pm.getFragmentation(), 0);
+
+    while (true) {
+        size_t p = pm.selectPeer();
+        if (p == 1) {
+            break;
+        }
+    }
+
+    // Grow the peer to a point where it needs to be reallocated.
+    pm.rescorePeer(1, 200);
+    BOOST_CHECK_EQUAL(pm.getSlotCount(), 600);
+    BOOST_CHECK_EQUAL(pm.getFragmentation(), 100);
+
+    for (int i = 0; i < 25; i++) {
+        while (true) {
+            size_t p = pm.selectPeer();
+            BOOST_CHECK(p < 5);
+            BOOST_CHECK(p != 1);
+            if (p == 4) {
+                break;
+            }
+        }
+    }
+}
+
 BOOST_AUTO_TEST_SUITE_END()