diff --git a/deps/v8/src/base/platform/platform-posix.cc b/deps/v8/src/base/platform/platform-posix.cc
index 252d2137552..bb004d207e4 100644
--- a/deps/v8/src/base/platform/platform-posix.cc
+++ b/deps/v8/src/base/platform/platform-posix.cc
@@ -323,8 +323,12 @@ int OS::GetCurrentProcessId() {
 int OS::GetCurrentThreadId() {
 #if defined(ANDROID)
   return static_cast<int>(syscall(__NR_gettid));
-#else
+#elif defined(SYS_gettid)
   return static_cast<int>(syscall(SYS_gettid));
+#else
+  // PNaCL doesn't have a way to get an integral thread ID, but it doesn't
+  // really matter, because we only need it in PerfJitLogger::LogRecordedBuffer.
+  return 0;
 #endif  // defined(ANDROID)
 }
 
diff --git a/deps/v8/src/base/platform/platform.h b/deps/v8/src/base/platform/platform.h
index 8a541262685..9567572d800 100644
--- a/deps/v8/src/base/platform/platform.h
+++ b/deps/v8/src/base/platform/platform.h
@@ -35,6 +35,7 @@ namespace std {
 int signbit(double x);
 }
 # endif
+#include <alloca.h>
 #endif
 
 #if V8_OS_QNX