diff --git a/lib/sanitizer_common/sanitizer_unwind_linux_libcdep.cpp b/lib/sanitizer_common/sanitizer_unwind_linux_libcdep.cpp
index 1a43759..7277774 100644
--- a/lib/sanitizer_common/sanitizer_unwind_linux_libcdep.cpp
+++ b/lib/sanitizer_common/sanitizer_unwind_linux_libcdep.cpp
@@ -27,6 +27,8 @@
 
 namespace __sanitizer {
 
+namespace {
+
 //---------------------------- UnwindSlow --------------------------------------
 
 typedef struct {
@@ -119,6 +121,8 @@
   return UNWIND_CONTINUE;
 }
 
+}  // namespace
+
 void BufferedStackTrace::UnwindSlow(uptr pc, u32 max_depth) {
   CHECK_GE(max_depth, 2);
   size = 0;