--- a/third_party/crashpad/crashpad/compat/linux/sys/ptrace.h
+++ b/third_party/crashpad/crashpad/compat/linux/sys/ptrace.h
@@ -17,8 +17,6 @@
 
 #include_next <sys/ptrace.h>
 
-#include <sys/cdefs.h>
-
 // https://sourceware.org/bugzilla/show_bug.cgi?id=22433
 #if !defined(PTRACE_GET_THREAD_AREA) && !defined(PT_GET_THREAD_AREA) && \
     defined(__GLIBC__)
--- a/third_party/libsync/src/include/sync/sync.h
+++ b/third_party/libsync/src/include/sync/sync.h
@@ -19,12 +19,13 @@
 #ifndef __SYS_CORE_SYNC_H
 #define __SYS_CORE_SYNC_H
 
-#include <sys/cdefs.h>
 #include <stdint.h>
 
 #include <linux/types.h>
 
-__BEGIN_DECLS
+#ifdef __cplusplus
+extern "C" {
+#endif
 
 struct sync_legacy_merge_data {
  int32_t fd2;
@@ -158,6 +159,8 @@
                                   struct sync_pt_info *itr);
 void sync_fence_info_free(struct sync_fence_info_data *info);
 
-__END_DECLS
+#ifdef __cplusplus
+}
+#endif
 
 #endif /* __SYS_CORE_SYNC_H */