diff --git a/VoldCommand.h b/VoldCommand.h
index 5ddc666..e435159 100644
--- a/VoldCommand.h
+++ b/VoldCommand.h
@@ -21,7 +21,7 @@
 
 class VoldCommand : public FrameworkCommand {
 public:
-    VoldCommand(const char *cmd);
+    explicit VoldCommand(const char *cmd);
     virtual ~VoldCommand() {}
 };