diff --git a/src/flatland/protobuf/PersistentProtocolBufferMap.java b/src/flatland/protobuf/PersistentProtocolBufferMap.java
index 640466e..4042415 100644
--- a/src/flatland/protobuf/PersistentProtocolBufferMap.java
+++ b/src/flatland/protobuf/PersistentProtocolBufferMap.java
@@ -173,6 +173,10 @@ public DynamicMessage parseFrom(CodedInputStream input) throws IOException {
       return DynamicMessage.parseFrom(type, input);
     }
 
+    public DynamicMessage parseFrom(InputStream input) throws IOException {
+        return DynamicMessage.parseFrom(type, input);
+    }
+
     public DynamicMessage.Builder parseDelimitedFrom(InputStream input) throws IOException {
       DynamicMessage.Builder builder = newBuilder();
       if (builder.mergeDelimitedFrom(input)) {
@@ -305,6 +309,18 @@ static public PersistentProtocolBufferMap parseFrom(Def def, CodedInputStream in
     return new PersistentProtocolBufferMap(null, def, message);
   }
 
+  static public PersistentProtocolBufferMap parseFrom(Def def, InputStream input)
+          throws IOException {
+    DynamicMessage message = def.parseFrom(input);
+    return new PersistentProtocolBufferMap(null, def, message);
+  }
+
+  static public PersistentProtocolBufferMap parseFrom(Def def, byte[] input)
+          throws IOException {
+    DynamicMessage message = def.parseFrom(input);
+    return new PersistentProtocolBufferMap(null, def, message);
+  }
+
   static public PersistentProtocolBufferMap parseDelimitedFrom(Def def, InputStream input)
           throws IOException {
     DynamicMessage.Builder builder = def.parseDelimitedFrom(input);
@@ -361,6 +377,10 @@ public byte[] toByteArray() {
     return message().toByteArray();
   }
 
+  public void writeTo(OutputStream output) throws IOException {
+    message().writeTo(output);
+  }
+
   public void writeTo(CodedOutputStream output) throws IOException {
     message().writeTo(output);
   }
@@ -369,6 +389,15 @@ public void writeDelimitedTo(OutputStream output) throws IOException {
     message().writeDelimitedTo(output);
   }
 
+  public int getSerializedSize() {
+    return message().getSerializedSize();
+  }
+
+  public int getDelimitedSize() {
+      int serializedSize = getSerializedSize();
+      return CodedOutputStream.computeRawVarint32Size(serializedSize) + serializedSize;
+  }
+
   public Descriptors.Descriptor getMessageType() {
     return def.getMessageType();
   }
diff --git a/src/flatland/protobuf/core.clj b/src/flatland/protobuf/core.clj
index 1a0431d..03ccb7e 100644
--- a/src/flatland/protobuf/core.clj
+++ b/src/flatland/protobuf/core.clj
@@ -104,3 +104,18 @@
   "Get value at key ignoring extension fields."
   [^PersistentProtocolBufferMap p key]
   (.getValAt p key false))
+
+(defn serialized-size
+  "Get the number of bytes required to encode this message.  The result is only
+  computed on the first call and memoized after that."
+  [^PersistentProtocolBufferMap p]
+  (when p
+    (.getSerializedSize p)))
+
+(defn delimited-size
+  "Get the number of bytes required to encode this message with a length
+   delimiter.  The result is only computed on the first call and memoized after
+   that."
+  [^PersistentProtocolBufferMap p]
+  (when p
+    (.getDelimitedSize p)))
diff --git a/test/flatland/protobuf/core_test.clj b/test/flatland/protobuf/core_test.clj
index a45b0b6..96b2277 100644
--- a/test/flatland/protobuf/core_test.clj
+++ b/test/flatland/protobuf/core_test.clj
@@ -3,7 +3,7 @@
         [flatland.io.core :only [catbytes]]
         [flatland.useful.utils :only [adjoin]]
         ordered-map.core)
-  (:import (java.io PipedInputStream PipedOutputStream)))
+  (:import (java.io PipedInputStream PipedOutputStream ByteArrayOutputStream)))
 
 (def Foo      (protodef flatland.protobuf.test.Core$Foo))
 (def FooUnder (protodef flatland.protobuf.test.Core$Foo
@@ -463,4 +463,20 @@
   (is (thrown-with-msg? IllegalArgumentException #"error setting string field flatland.protobuf.test.core.Foo.label to 8"
         (protobuf Foo :label 8)))
   (is (thrown-with-msg? IllegalArgumentException #"error adding 1 to string field flatland.protobuf.test.core.Foo.tags"
-        (protobuf Foo :tags [1 2 3]))))
\ No newline at end of file
+        (protobuf Foo :tags [1 2 3]))))
+
+(deftest test-serialized-size
+  (let [p (protobuf Foo :id 5 :tags ["fast" "shiny"] :label "nice")
+        q (protobuf Foo :id 5 :tags ["fast"])]
+    (is (= (serialized-size p) (alength (protobuf-dump p))))
+    (is (= (serialized-size q) (alength (protobuf-dump q))))))
+
+(deftest test-delimited-size
+  (let [p (protobuf Foo :id 5 :tags ["fast" "shiny"] :label "nice")
+        q (protobuf Foo :id 5 :tags ["fast"])
+        p-out (ByteArrayOutputStream.)
+        q-out (ByteArrayOutputStream.)]
+    (protobuf-write p-out p)
+    (protobuf-write q-out q)
+    (is (= (delimited-size p) (alength (.toByteArray p-out))))
+    (is (= (delimited-size q) (alength (.toByteArray q-out))))))