diff --git a/configure.ac b/configure.ac
index 4902c2b..f7f69a0 100644
--- a/configure.ac
+++ b/configure.ac
@@ -79,7 +79,7 @@
 ])
 
 # Checks for typedefs, structures, and compiler characteristics.
-AX_CXX_COMPILE_STDCXX([17], [noext], [mandatory])
+AX_CXX_COMPILE_STDCXX([20], [noext], [mandatory])
 AX_APPEND_COMPILE_FLAGS([-Wall -Werror], [CFLAGS])
 AX_APPEND_COMPILE_FLAGS([-Wall -Werror], [CXXFLAGS])