diff --git a/cmake/DaemonFlags.cmake b/cmake/DaemonFlags.cmake
index 906ed93a8a..179835ddca 100644
--- a/cmake/DaemonFlags.cmake
+++ b/cmake/DaemonFlags.cmake
@@ -363,13 +363,23 @@ else()
 				message(FATAL_ERROR "GNU++23 is not supported by the compiler")
 			endif()
 		else()
-			# PNaCl only defines isascii if __STRICT_ANSI__ is not defined,
-			# always prefer GNU dialect.
-			try_cxx_flag(GNUXX14 "-std=gnu++14")
-			if (NOT FLAG_GNUXX14)
-				try_cxx_flag(GNUXX1Y "-std=gnu++1y")
-				if (NOT FLAG_GNUXX1Y)
-					message(FATAL_ERROR "GNU++14 is not supported by the compiler")
+			if (YOKAI_TARGET_SYSTEM_NACL AND NOT USE_NACL_SAIGO)
+				# PNaCl only defines isascii if __STRICT_ANSI__ is not defined,
+				# always prefer GNU dialect.
+				try_cxx_flag(GNUXX14 "-std=gnu++14")
+				if (NOT FLAG_GNUXX14)
+					try_cxx_flag(GNUXX1Y "-std=gnu++1y")
+					if (NOT FLAG_GNUXX1Y)
+						message(FATAL_ERROR "GNU++14 is not supported by the compiler")
+					endif()
+				endif()
+			else()
+				try_cxx_flag(GNUXX20 "-std=gnu++20")
+				if (NOT FLAG_GNUXX20)
+					try_cxx_flag(GNUXX2Y "-std=gnu++2a")
+					if (NOT FLAG_GNUXX2Y)
+						message(FATAL_ERROR "GNU++20 is not supported by the compiler")
+					endif()
 				endif()
 			endif()
 		endif()