diff --git a/atom/browser/javascript_environment.h b/atom/browser/javascript_environment.h
index 046ba3e29c..43a7295f90 100644
--- a/atom/browser/javascript_environment.h
+++ b/atom/browser/javascript_environment.h
@@ -45,7 +45,7 @@ class JavascriptEnvironment {
 // Manage the Node Environment automatically.
 class NodeEnvironment {
  public:
-  NodeEnvironment(node::Environment* env);
+  explicit NodeEnvironment(node::Environment* env);
   ~NodeEnvironment();
 
  private: