diff --git a/docshell/base/LoadContext.h b/docshell/base/LoadContext.h
index 1607eeddbe77..e5949ae6e9d9 100644
--- a/docshell/base/LoadContext.h
+++ b/docshell/base/LoadContext.h
@@ -107,7 +107,7 @@ public:
 
   // Constructor for creating a LoadContext with a given principal's appId and
   // browser flag.
-  LoadContext(nsIPrincipal* aPrincipal);
+  explicit LoadContext(nsIPrincipal* aPrincipal);
 
 private:
   ~LoadContext() {}