diff --git a/include/Lexesis/template.h b/include/Lexesis/template.h
index d8e76c9..1831e34 100644
--- a/include/Lexesis/template.h
+++ b/include/Lexesis/template.h
@@ -12,7 +12,7 @@ namespace templ {
     using TemplateContext = mstch::node;
 
     TemplateContext make_string(std::string);
-    TemplateContext make_map(std::map<std::string, TemplateContext>);
+    TemplateContext make_map(std::map<const std::string, TemplateContext>);
     TemplateContext make_array(std::vector<TemplateContext>);
 
     class Template {
diff --git a/src/backends/cpp.cpp b/src/backends/cpp.cpp
index 20092c3..7aa4ebe 100644
--- a/src/backends/cpp.cpp
+++ b/src/backends/cpp.cpp
@@ -26,7 +26,7 @@ namespace lxs { namespace backends {
         std::unique_ptr<std::ostream> headerStream = getOstreamForFileName(lexerName + ".h");
         std::unique_ptr<std::ostream> implementationStream  = getOstreamForFileName(lexerName + ".cpp");
 
-        std::map<std::string, templ::TemplateContext> topLevel;
+        std::map<const std::string, templ::TemplateContext> topLevel;
         
         lexerName[0] = std::toupper(lexerName[0]);
         topLevel["name"] = templ::make_string(lexerName);