diff --git a/libc/bionic/pthread.c b/libc/bionic/pthread.c
index 0a0854d..1da2ec9 100644
--- a/libc/bionic/pthread.c
+++ b/libc/bionic/pthread.c
@@ -49,6 +49,7 @@
 #include <sys/stat.h>
 #include <fcntl.h>
 #include <stdio.h>
+#include <bionic_pthread.h>
 
 extern int  __pthread_clone(int (*fn)(void*), void *child_stack, int flags, void *arg);
 extern void _exit_with_stack_teardown(void * stackBase, int stackSize, int retCode);
@@ -1964,3 +1965,15 @@
     errno = saved_errno;
     return ret;
 }
+
+/* Return the kernel thread ID for a pthread.
+ * This is only defined for implementations where pthread <-> kernel is 1:1, which this is.
+ * Not the same as pthread_getthreadid_np, which is commonly defined to be opaque.
+ * Internal, not an NDK API.
+ */
+
+pid_t __pthread_gettid(pthread_t thid)
+{
+    pthread_internal_t* thread = (pthread_internal_t*)thid;
+    return thread->kernel_id;
+}
diff --git a/libc/private/bionic_pthread.h b/libc/private/bionic_pthread.h
new file mode 100644
index 0000000..07bcbd4
--- /dev/null
+++ b/libc/private/bionic_pthread.h
@@ -0,0 +1,41 @@
+/*
+ * Copyright (C) 2011 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#ifndef _BIONIC_PTHREAD_H
+#define _BIONIC_PTHREAD_H
+
+#include <sys/cdefs.h>
+
+__BEGIN_DECLS
+
+/* Internal, not an NDK API */
+extern pid_t __pthread_gettid(pthread_t thid);
+
+__END_DECLS
+
+#endif /* _BIONIC_PTHREAD_H */