diff --git a/CMakeLists.txt b/CMakeLists.txt
index bd1e0be0..9aeb4b14 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -78,7 +78,7 @@ if (CMAKE_CXX_COMPILER_ID MATCHES "GNU")
       -Wcast-align -Wnon-virtual-dtor
       -Wctor-dtor-privacy -Wdisabled-optimization
       -Winvalid-pch -Woverloaded-virtual
-      -Wconversion
+      -Wconversion -Wswitch-enum
       -Wno-ctor-dtor-privacy -Wno-format-nonliteral -Wno-shadow)
   if (NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS 4.6)
       set(PEDANTIC_COMPILE_FLAGS ${PEDANTIC_COMPILE_FLAGS} -Wnoexcept
diff --git a/test/scan.h b/test/scan.h
index ace84f77..50ac0941 100644
--- a/test/scan.h
+++ b/test/scan.h
@@ -201,7 +201,8 @@ struct scan_handler : error_handler {
       scan_ctx_.advance_to(it);
       break;
     }
-    default:
+    case scan_type::none_type:
+    case scan_type::custom_type:
       assert(false);
     }
   }