diff --git a/src/data/StructLayout.hpp b/src/data/StructLayout.hpp
index 35942457..c0d27229 100644
--- a/src/data/StructLayout.hpp
+++ b/src/data/StructLayout.hpp
@@ -15,7 +15,7 @@ namespace data {
         COUNT
     };
 
-    inline const char* to_string(FieldType type) {
+    inline std::string to_string(FieldType type) {
         const char* names[] = {
             "int8", "int16", "int32", "int64", "float32", "float64", "char" 
         };