diff --git a/src/NetVips/VipsProgress.cs b/src/NetVips/VipsProgress.cs
index 1346aaf4..3f101129 100644
--- a/src/NetVips/VipsProgress.cs
+++ b/src/NetVips/VipsProgress.cs
@@ -22,7 +22,7 @@ public struct GTimer
         /// <summary>
         /// Is the timer currently active?
         /// </summary>
-        public int Active;
+        public bool Active;
     }
 
     /// <summary>