diff --git a/src/compiler_llvm/compiler_llvm.cc b/src/compiler_llvm/compiler_llvm.cc
index 1623b2c..ca0a4da 100644
--- a/src/compiler_llvm/compiler_llvm.cc
+++ b/src/compiler_llvm/compiler_llvm.cc
@@ -258,6 +258,8 @@
 
   EnsureCompilationUnit();
 
+  MutexLock GUARD_CUNIT(curr_cunit_->cunit_lock_);
+
   UniquePtr<MethodCompiler> method_compiler(
       new MethodCompiler(curr_cunit_, compiler_, oat_compilation_unit));
 
@@ -271,6 +273,8 @@
 
   EnsureCompilationUnit();
 
+  MutexLock GUARD_CUNIT(curr_cunit_->cunit_lock_);
+
   UniquePtr<JniCompiler> jni_compiler(
       new JniCompiler(curr_cunit_, *compiler_, oat_compilation_unit));
 
@@ -284,6 +288,8 @@
 
   EnsureCompilationUnit();
 
+  MutexLock GUARD_CUNIT(curr_cunit_->cunit_lock_);
+
   UniquePtr<UpcallCompiler> upcall_compiler(
     new UpcallCompiler(curr_cunit_, *compiler_));