diff --git a/src/core/include/mp-units/bits/external/hacks.h b/src/core/include/mp-units/bits/external/hacks.h
index cbe2b05b..a24a884a 100644
--- a/src/core/include/mp-units/bits/external/hacks.h
+++ b/src/core/include/mp-units/bits/external/hacks.h
@@ -83,7 +83,7 @@
 // TODO revise the below when clang-18 is released
 #if MP_UNITS_COMP_CLANG >= 18 && !defined __cpp_explicit_this_parameter
 
-#define __cpp_explicit_this_parameter
+#define __cpp_explicit_this_parameter 202110L
 
 #endif