diff --git a/base/array.c b/base/array.c
index 7b0d77b1c..9266411aa 100644
--- a/base/array.c
+++ b/base/array.c
@@ -218,7 +218,7 @@ heim_array_delete_value(heim_array_t array, size_t idx)
  */
 
 void
-heim_array_filter(heim_array_t array, bool (^block)(heim_object_t))
+heim_array_filter(heim_array_t array, int (^block)(heim_object_t))
 {
     size_t n = 0;
 
diff --git a/base/heimbase.h b/base/heimbase.h
index 4dfeb2fac..0e7b9f021 100644
--- a/base/heimbase.h
+++ b/base/heimbase.h
@@ -131,7 +131,7 @@ heim_object_t
 	heim_array_copy_value(heim_array_t, size_t);
 void	heim_array_delete_value(heim_array_t, size_t);
 #ifdef __BLOCKS__
-void	heim_array_filter(heim_array_t, bool (^)(heim_object_t));
+void	heim_array_filter(heim_array_t, int (^)(heim_object_t));
 #endif
 
 /*