diff --git a/tools/tool_errors.hpp b/tools/tool_errors.hpp
index af99c2c..cf898e6 100644
--- a/tools/tool_errors.hpp
+++ b/tools/tool_errors.hpp
@@ -3,6 +3,9 @@
 #include <exception>
 #include <string>
 
+namespace host_tool
+{
+
 class ToolException : public std::exception
 {
   public:
@@ -16,3 +19,5 @@
   private:
     std::string message;
 };
+
+} // namespace host_tool