diff --git a/src/cpp/presents/data/ClientObject.h b/src/cpp/presents/data/ClientObject.h
index 8448b193b..3b1a6f087 100644
--- a/src/cpp/presents/data/ClientObject.h
+++ b/src/cpp/presents/data/ClientObject.h
@@ -5,10 +5,10 @@
 #include "presents/ObjectOutputStream.h"
 #include "presents/streamers/StreamableStreamer.h"
 
-#include "presents/dobj/DObject.h"
-#include "util/Name.h"
 #include "presents/data/PermissionPolicy.h"
+#include "presents/dobj/DObject.h"
 #include "presents/dobj/DSet.h"
+#include "util/Name.h"
 
 namespace presents { namespace data { 
 
diff --git a/src/cpp/presents/dobj/EntryAddedEvent.h b/src/cpp/presents/dobj/EntryAddedEvent.h
index 1442887f0..b19b59548 100644
--- a/src/cpp/presents/dobj/EntryAddedEvent.h
+++ b/src/cpp/presents/dobj/EntryAddedEvent.h
@@ -5,8 +5,8 @@
 #include "presents/ObjectOutputStream.h"
 #include "presents/streamers/StreamableStreamer.h"
 
-#include "presents/dobj/NamedEvent.h"
 #include "presents/Streamable.h"
+#include "presents/dobj/NamedEvent.h"
 
 namespace presents { namespace dobj { 
 
diff --git a/src/cpp/presents/dobj/EntryRemovedEvent.h b/src/cpp/presents/dobj/EntryRemovedEvent.h
index ec1795960..89fd01da9 100644
--- a/src/cpp/presents/dobj/EntryRemovedEvent.h
+++ b/src/cpp/presents/dobj/EntryRemovedEvent.h
@@ -5,8 +5,8 @@
 #include "presents/ObjectOutputStream.h"
 #include "presents/streamers/StreamableStreamer.h"
 
-#include "presents/dobj/NamedEvent.h"
 #include "presents/Streamable.h"
+#include "presents/dobj/NamedEvent.h"
 
 namespace presents { namespace dobj { 
 
diff --git a/src/cpp/presents/net/AuthRequest.h b/src/cpp/presents/net/AuthRequest.h
index 9d736f5d3..a86295ff4 100644
--- a/src/cpp/presents/net/AuthRequest.h
+++ b/src/cpp/presents/net/AuthRequest.h
@@ -5,8 +5,8 @@
 #include "presents/ObjectOutputStream.h"
 #include "presents/streamers/StreamableStreamer.h"
 
-#include "presents/net/UpstreamMessage.h"
 #include "presents/net/Credentials.h"
+#include "presents/net/UpstreamMessage.h"
 
 namespace presents { namespace net { 
 
diff --git a/src/cpp/presents/net/BootstrapData.h b/src/cpp/presents/net/BootstrapData.h
index c98b2e6e0..b016b42cb 100644
--- a/src/cpp/presents/net/BootstrapData.h
+++ b/src/cpp/presents/net/BootstrapData.h
@@ -5,8 +5,8 @@
 #include "presents/ObjectOutputStream.h"
 #include "presents/streamers/StreamableStreamer.h"
 
-#include "presents/data/InvocationMarshaller.h"
 #include "presents/Streamable.h"
+#include "presents/data/InvocationMarshaller.h"
 
 namespace presents { namespace net { 
 
diff --git a/src/cpp/presents/net/EventNotification.h b/src/cpp/presents/net/EventNotification.h
index faddeb045..5c6e3696e 100644
--- a/src/cpp/presents/net/EventNotification.h
+++ b/src/cpp/presents/net/EventNotification.h
@@ -5,8 +5,8 @@
 #include "presents/ObjectOutputStream.h"
 #include "presents/streamers/StreamableStreamer.h"
 
-#include "presents/net/DownstreamMessage.h"
 #include "presents/dobj/DEvent.h"
+#include "presents/net/DownstreamMessage.h"
 
 namespace presents { namespace net { 
 
diff --git a/src/cpp/presents/net/ForwardEventRequest.h b/src/cpp/presents/net/ForwardEventRequest.h
index 13d38b60d..a0d1cc6c7 100644
--- a/src/cpp/presents/net/ForwardEventRequest.h
+++ b/src/cpp/presents/net/ForwardEventRequest.h
@@ -5,8 +5,8 @@
 #include "presents/ObjectOutputStream.h"
 #include "presents/streamers/StreamableStreamer.h"
 
-#include "presents/net/UpstreamMessage.h"
 #include "presents/dobj/DEvent.h"
+#include "presents/net/UpstreamMessage.h"
 
 namespace presents { namespace net { 
 
diff --git a/src/cpp/presents/net/UsernamePasswordCreds.h b/src/cpp/presents/net/UsernamePasswordCreds.h
index 60898aa3a..2f60c8787 100644
--- a/src/cpp/presents/net/UsernamePasswordCreds.h
+++ b/src/cpp/presents/net/UsernamePasswordCreds.h
@@ -5,8 +5,8 @@
 #include "presents/ObjectOutputStream.h"
 #include "presents/streamers/StreamableStreamer.h"
 
-#include "util/Name.h"
 #include "presents/net/Credentials.h"
+#include "util/Name.h"
 
 namespace presents { namespace net { 
 
diff --git a/src/main/java/com/threerings/presents/tools/cpp/GenCPPReceiverTask.java b/src/main/java/com/threerings/presents/tools/cpp/GenCPPReceiverTask.java
index c2a1eefbd..a11bda6b6 100644
--- a/src/main/java/com/threerings/presents/tools/cpp/GenCPPReceiverTask.java
+++ b/src/main/java/com/threerings/presents/tools/cpp/GenCPPReceiverTask.java
@@ -42,8 +42,8 @@ public class GenCPPReceiverTask extends GenReceiverTask
         CPPUtil.writeTemplate(DECODER_HEADER_TMPL, _cpproot,
             CPPUtil.makePath(namespaces, dname, ".h"), ctx);
 
-        Set<String> receiverHeaderIncludes = Sets.newHashSet();
-        Set<String> decoderImplIncludes = Sets.newHashSet();
+        Set<String> receiverHeaderIncludes = Sets.newTreeSet();
+        Set<String> decoderImplIncludes = Sets.newTreeSet();
         for (ServiceMethod meth : methods) {
             for (Type type : meth.method.getGenericParameterTypes()) {
                 CPPType cppType = new CPPType(type);
diff --git a/src/main/java/com/threerings/presents/tools/cpp/GenCPPServiceTask.java b/src/main/java/com/threerings/presents/tools/cpp/GenCPPServiceTask.java
index 3f51701f0..ee58ad192 100644
--- a/src/main/java/com/threerings/presents/tools/cpp/GenCPPServiceTask.java
+++ b/src/main/java/com/threerings/presents/tools/cpp/GenCPPServiceTask.java
@@ -41,8 +41,8 @@ public class GenCPPServiceTask extends GenServiceTask
         ctx.put("listeners", sdesc.listeners);
         ctx.put("argbuilder", new CPPArgBuilder(true));
 
-        Set<String> includes = Sets.newHashSet();
-        Set<String> implIncludes = Sets.newHashSet();
+        Set<String> includes = Sets.newTreeSet();
+        Set<String> implIncludes = Sets.newTreeSet();
         for (ServiceMethod meth : sdesc.methods) {
             for (Type type : meth.method.getGenericParameterTypes()) {
                 CPPType cppType = new CPPType(type);
diff --git a/src/main/java/com/threerings/presents/tools/cpp/GenCPPStreamableTask.java b/src/main/java/com/threerings/presents/tools/cpp/GenCPPStreamableTask.java
index 5d67e6696..486b8f2cb 100644
--- a/src/main/java/com/threerings/presents/tools/cpp/GenCPPStreamableTask.java
+++ b/src/main/java/com/threerings/presents/tools/cpp/GenCPPStreamableTask.java
@@ -91,8 +91,8 @@ public class GenCPPStreamableTask extends GenTask
         ctx.put("javaName", sclass.getName());
         ctx.put("namespace", CPPUtil.makeNamespace(sclass));
 
-        Set<String> headerIncludes = Sets.newHashSet();
-        Set<String> implIncludes = Sets.newHashSet();
+        Set<String> headerIncludes = Sets.newTreeSet();
+        Set<String> implIncludes = Sets.newTreeSet();
         if (needSuper) {
             ctx.put("super", makeCPPName(sclass.getSuperclass()));
             addInclude(sclass.getSuperclass(), headerIncludes);