diff --git a/compiler/optimizing/graph_visualizer.cc b/compiler/optimizing/graph_visualizer.cc
index 9419c8d..601bebd 100644
--- a/compiler/optimizing/graph_visualizer.cc
+++ b/compiler/optimizing/graph_visualizer.cc
@@ -40,7 +40,7 @@
 #include "ssa_liveness_analysis.h"
 #include "utils/assembler.h"
 
-namespace art {
+namespace art HIDDEN {
 
 static bool HasWhitespace(const char* str) {
   DCHECK(str != nullptr);