diff --git a/src/compiler/codegen/Optimizer.h b/src/compiler/codegen/Optimizer.h
index 307d401..74a5b75 100644
--- a/src/compiler/codegen/Optimizer.h
+++ b/src/compiler/codegen/Optimizer.h
@@ -19,6 +19,8 @@
 
 #include "../Dalvik.h"
 
+namespace art {
+
 #define STACK_ALIGN_WORDS 4
 #define STACK_ALIGNMENT (STACK_ALIGN_WORDS * 4)
 
@@ -29,4 +31,6 @@
 void oatApplyLocalOptimizations(struct CompilationUnit* cUnit,
                                 struct LIR* head, struct LIR* tail);
 
+}  // namespace art
+
 #endif  // ART_SRC_COMPILER_COMPILER_OPTIMIZATION_H_