diff --git a/.github/workflows/parsey.yml b/.github/workflows/parsey.yml
index a7416952b6d49e..3d5e314eaf6e2c 100644
--- a/.github/workflows/parsey.yml
+++ b/.github/workflows/parsey.yml
@@ -73,6 +73,8 @@ jobs:
 
       - run: make
 
+      - run: make TESTRUN_SCRIPT='-e "exit !RUBY_DESCRIPTION.include?(%[+PRISM])"' run
+
       - name: make ${{ matrix.test_task }}
         run: make -s ${{ matrix.test_task }} RUN_OPTS="$RUN_OPTS" SPECOPTS="$SPECOPTS"
         env:
diff --git a/configure.ac b/configure.ac
index 30e197bf973448..5899f2aa9c88f6 100644
--- a/configure.ac
+++ b/configure.ac
@@ -4547,10 +4547,10 @@ AS_IF([test x"$enable_rubygems" = xno], [
 AC_SUBST(USE_RUBYGEMS)
 
 m4_define(available_parsers, [parse.y, prism])
-with_parser=prism
 AC_ARG_WITH(parser,
     AS_HELP_STRING([--with-parser=PARSER],
-        [specify default parser; PARSER is one of ]m4_join([, ],available_parsers)))
+        [specify default parser; PARSER is one of ]m4_join([, ],available_parsers)),
+    [], [with_parser=prism])
 AS_CASE([$with_parser],
 m4_foreach(parser, [available_parsers],
     parser[,][AC_DEFINE_UNQUOTED(RB_DEFAULT_PARSER, RB_DEFAULT_PARSER_[]AS_TR_CPP(parser)),])