diff --git a/app/paint/gimppaintcore-loops.cc b/app/paint/gimppaintcore-loops.cc
index 3211fc63cc..355da25785 100644
--- a/app/paint/gimppaintcore-loops.cc
+++ b/app/paint/gimppaintcore-loops.cc
@@ -97,7 +97,7 @@ extern "C"
  */
 
 
-enum
+enum Algorithm : guint
 {
   ALGORITHM_PAINT_BUF              = 1u << 31,
   ALGORITHM_PAINT_MASK             = 1u << 30,