diff --git a/xo-indentlog/include/xo/indentlog/print/ppdetail_atomic.hpp b/xo-indentlog/include/xo/indentlog/print/ppdetail_atomic.hpp
index 3f460a76..3f2a3c3f 100644
--- a/xo-indentlog/include/xo/indentlog/print/ppdetail_atomic.hpp
+++ b/xo-indentlog/include/xo/indentlog/print/ppdetail_atomic.hpp
@@ -13,10 +13,14 @@ namespace xo {
         struct ppstate; // see pretty.hpp
         struct ppindentinfo;
 
-        // Defining this means ppdetail_atomic is not used.
+        // Defining this means ppdetail_atomic -> ppdetail.
+        // For debugging suppress the #define; causes specialization of ppdetail_atomic to be required for every T
+        // that participates in pretty printing
+        //
         // In that case where not explicitly specialized ppdetail will revert to ordinary printing for a type,
         // instead of giving compile-time error about missing template specialization of ppdetail.
-//#define ppdetail_atomic ppdetail
+        //
+#define ppdetail_atomic ppdetail
 
         struct ppindentinfo {
             ppindentinfo(ppstate * pps, std::uint32_t ci0, std::uint32_t indent_width, bool upto)