diff --git thrift/lib/cpp2/server/Cpp2ConnContext.cpp thrift/lib/cpp2/server/Cpp2ConnContext.cpp
index cc60e540..fb90e334 100644
--- thrift/lib/cpp2/server/Cpp2ConnContext.cpp
+++ thrift/lib/cpp2/server/Cpp2ConnContext.cpp
@@ -22,6 +22,10 @@
 #include <sys/ucred.h> // @manual
 #endif
 
+#ifndef SOL_LOCAL
+#define SOL_LOCAL 0
+#endif
+
 namespace {
 
 #ifndef _WIN32
@@ -62,6 +66,7 @@ Cpp2ConnContext::PeerCred Cpp2ConnContext::PeerCred::queryFromSocket(
     return PeerCred{ErrorRetrieving, errnoToUid(errno), 0};
   } else {
 #ifdef __APPLE__
+#ifdef LOCAL_PEEREPID
     pid_t epid = 0;
     if (getsockopt(
             socket.toFd(),
@@ -73,6 +74,11 @@ Cpp2ConnContext::PeerCred Cpp2ConnContext::PeerCred::queryFromSocket(
     } else {
       return PeerCred{epid, cred.cr_uid, cred.cr_gid};
     }
+#else
+    // Old SDKs have no LOCAL_PEEREPID and old kernels do not implement
+    // it; report the retrieved credentials with an unknown pid.
+    return PeerCred{0, cred.cr_uid, cred.cr_gid};
+#endif
 #else
     return PeerCred{cred.cr_pid, cred.cr_uid, cred.cr_gid};
 #endif
diff --git thrift/lib/cpp2/server/ParallelConcurrencyController.h thrift/lib/cpp2/server/ParallelConcurrencyController.h
index 24c55161..bcbfd290 100644
--- thrift/lib/cpp2/server/ParallelConcurrencyController.h
+++ thrift/lib/cpp2/server/ParallelConcurrencyController.h
@@ -16,6 +16,7 @@
 
 #pragma once
 
+#include <atomic>
 #include <limits>
 
 #include <folly/executors/MeteredExecutor.h>
@@ -92,12 +93,20 @@ class ParallelConcurrencyControllerBase : public ConcurrencyControllerBase,
 
   struct Counters {
     constexpr Counters() noexcept = default;
+#if ATOMIC_LLONG_LOCK_FREE == 2
     // Number of requests that are being executed
     // by the executor
     uint32_t requestInExecution{0};
     // Number of requests that sit in the queue waiting
     // to be dequeued by the ConcurrencyController
     uint32_t pendingDequeCalls{0};
+#else
+    // Half-width counters on targets without always-lock-free 8-byte
+    // atomics (e.g. ppc32), so that the struct stays lock-free; caps
+    // concurrent and pending requests at 65535.
+    uint16_t requestInExecution{0};
+    uint16_t pendingDequeCalls{0};
+#endif
   };
   static_assert(std::atomic<Counters>::is_always_lock_free);
 
diff --git thrift/lib/cpp2/transport/rocket/server/RefactoredRocketServerConnection.cpp thrift/lib/cpp2/transport/rocket/server/RefactoredRocketServerConnection.cpp
index 8f398c1c..4c3b0b59 100644
--- thrift/lib/cpp2/transport/rocket/server/RefactoredRocketServerConnection.cpp
+++ thrift/lib/cpp2/transport/rocket/server/RefactoredRocketServerConnection.cpp
@@ -54,6 +54,11 @@
 #include <thrift/lib/cpp2/transport/rocket/server/RocketStreamClientCallback.h>
 #include <thrift/lib/cpp2/transport/rocket/server/detail/OutgoingFrameHandler.h>
 
+// Missing from SDKs before 10.7; old kernels reject the option at runtime.
+#if defined(__APPLE__) && !defined(IPV6_TCLASS)
+#define IPV6_TCLASS 36
+#endif
+
 THRIFT_FLAG_DECLARE_bool(enable_rocket_connection_observers);
 THRIFT_FLAG_DECLARE_bool(thrift_check_free_stream_thread);
 THRIFT_FLAG_DEFINE_bool(rocket_use_outgoing_frame_handler, false);
diff --git thrift/lib/cpp2/transport/rocket/server/RocketServerConnection.cpp thrift/lib/cpp2/transport/rocket/server/RocketServerConnection.cpp
index 61f79532..f67a1d87 100644
--- thrift/lib/cpp2/transport/rocket/server/RocketServerConnection.cpp
+++ thrift/lib/cpp2/transport/rocket/server/RocketServerConnection.cpp
@@ -52,6 +52,11 @@
 #include <thrift/lib/cpp2/transport/rocket/server/RocketSinkClientCallback.h>
 #include <thrift/lib/cpp2/transport/rocket/server/RocketStreamClientCallback.h>
 
+// Missing from SDKs before 10.7; old kernels reject the option at runtime.
+#if defined(__APPLE__) && !defined(IPV6_TCLASS)
+#define IPV6_TCLASS 36
+#endif
+
 THRIFT_FLAG_DEFINE_bool(enable_rocket_connection_observers, false);
 THRIFT_FLAG_DEFINE_bool(thrift_enable_stream_counters, true);
 THRIFT_FLAG_DEFINE_bool(thrift_check_free_stream_thread, true);