diff --git a/include/openmc/cross_sections.h b/include/openmc/cross_sections.h
index 06140a6a8cf..091ac5a2779 100644
--- a/include/openmc/cross_sections.h
+++ b/include/openmc/cross_sections.h
@@ -17,13 +17,7 @@ namespace openmc {
 class Library {
 public:
   // Types, enums
-  enum class Type {
-    neutron = 1,
-    photon = 3,
-    thermal = 2,
-    multigroup = 4,
-    wmp = 5
-  };
+  enum class Type { neutron, photon, thermal, multigroup, wmp };
 
   // Constructors
   Library() {};