diff --git a/common.mk b/common.mk
index ff11693b30bb50..8feb982f6bda55 100644
--- a/common.mk
+++ b/common.mk
@@ -1226,12 +1226,13 @@ missing-srcs: $(srcdir)/missing/des_tables.c
 
 srcs: common-srcs missing-srcs srcs-enc srcs-doc
 
-RIPPER_SRCS = $(srcdir)/ext/ripper/ripper.c \
-	      $(srcdir)/ext/ripper/ripper_init.c \
-	      $(srcdir)/ext/ripper/eventids1.h \
-	      $(srcdir)/ext/ripper/eventids1.c \
-	      $(srcdir)/ext/ripper/eventids2table.c \
-	      # RIPPER_SRCS
+RIPPER_SRCS1 = $(srcdir)/ext/ripper/ripper.c
+RIPPER_SRCS2 = $(srcdir)/ext/ripper/ripper_init.c \
+	       $(srcdir)/ext/ripper/eventids1.h \
+	       $(srcdir)/ext/ripper/eventids1.c \
+	       $(srcdir)/ext/ripper/eventids2table.c \
+	       # RIPPER_SRCS2
+RIPPER_SRCS = $(RIPPER_SRCS1) $(RIPPER_SRCS2)
 
 EXT_SRCS = ripper_srcs \
 	   $(srcdir)/ext/rbconfig/sizeof/sizes.c \
@@ -1348,10 +1349,12 @@ dump_ast$(BUILD_EXEEXT): $(tooldir)/dump_ast.c $(LIBPRISM_OBJS)
 	$(Q) $(CC) $(CFLAGS) $(OUTFLAG)$@ $(INCFLAGS) $(tooldir)/dump_ast.c $(LIBPRISM_OBJS)
 
 build-tool/Makefile: $(tooldir)/dump_ast.mkmf.rb prism-srcs prism-incs
-	+$(BASERUBY) -s $(tooldir)/dump_ast.mkmf.rb "-INCFLAGS=$(INCFLAGS)" "-make=$(MAKE)" build-tool $(tooldir)/dump_ast.c dump_ast.$(OBJEXT) $(LIBPRISM_OBJS)
+	+$(BASERUBY) -s $(tooldir)/dump_ast.mkmf.rb \
+	    "-INCFLAGS=$(INCFLAGS)" "-make=$(MAKE)" "-objext=$(OBJEXT)" \
+	    build-tool $(tooldir)/dump_ast.c dump_ast.$(OBJEXT) $(LIBPRISM_OBJS)
 
 build-tool/dump_ast$(BUILD_EXEEXT): build-tool/Makefile
-	cd build-tool && MAKEFLAGS= MFLAGS= && unset MAKEFLAGS MFLAGS && $(MAKE)
+	cd build-tool && MAKEFLAGS= MFLAGS= && unset MAKEFLAGS MFLAGS && $(MAKE) Q=$(Q)
 
 clean-local:: clean-build-tool
 clean-build-tool:
@@ -1379,6 +1382,8 @@ $(RIPPER_SRCS): $(srcdir)/parse.y $(srcdir)/defs/id.def
 $(RIPPER_SRCS): $(srcdir)/ext/ripper/depend $(srcdir)/ext/ripper/extconf.rb
 $(RIPPER_SRCS): $(srcdir)/ext/ripper/tools/preproc.rb $(srcdir)/ext/ripper/tools/dsl.rb
 $(RIPPER_SRCS): $(srcdir)/ext/ripper/ripper_init.c.tmpl $(srcdir)/ext/ripper/eventids2.c
+$(RIPPER_SRCS2): $(RIPPER_SRCS1)
+$(RIPPER_SRCS1):
 	$(ECHO) generating $@
 	$(Q) $(CHDIR) $(@D) && \
 	$(CAT_DEPEND) depend | \
diff --git a/test/ruby/test_env.rb b/test/ruby/test_env.rb
index b77f3d09ba7154..48409f843566e9 100644
--- a/test/ruby/test_env.rb
+++ b/test/ruby/test_env.rb
@@ -197,6 +197,7 @@ def test_keys
 
   def test_keys_encoding
     bug20958 = '[ruby-core:120277] [Bug #20958]'
+    omit "locale encoding is not UTF-8" unless ENCODING == Encoding::UTF_8
     orig = ENV.to_hash
     ENV.clear
     key = "TEST20958\u{30c6 30b9 30c8}"
@@ -206,14 +207,15 @@ def test_keys_encoding
       omit "platform does not support UTF-8 environment variables."
     end
     EnvUtil.with_default_internal(nil) do
-      enc = RUBY_PLATFORM =~ /mswin|mingw/ ?
-         Encoding::UTF_8 : Encoding.find("locale")
-      assert_equal(enc, ENV.keys.last.encoding, bug20958)
-      assert_equal(key.encode(enc), ENV.keys.last, bug20958)
+      assert_equal(ENCODING, ENV.keys.last.encoding, bug20958)
+      assert_equal(key.encode(ENCODING), ENV.keys.last, bug20958)
     end
 
     ENV.update(orig) #required to restore ENV[RbConfig::CONFIG['LIBPATHENV']]
-    env = {key => "x", "LOCALE" => "en_US.UTF-8", "LC_ALL" => "en_US.UTF-8"}
+    env = {key => "x"}
+    # invoke_ruby forces the C locale, restore the locale of this process,
+    # which is known to be UTF-8 here.
+    EnvUtil::LANG_ENVS.each {|e| env[e] = ENV[e]}
     load_path = $LOAD_PATH.map {|v| "-I#{v}" }
     internal_enc = "Windows-31J"
     params = [env, *load_path, "-Eutf-8:#{internal_enc}"]
diff --git a/tool/dump_ast.mkmf.rb b/tool/dump_ast.mkmf.rb
index eec6b72f79b520..8382fe2b5207d9 100755
--- a/tool/dump_ast.mkmf.rb
+++ b/tool/dump_ast.mkmf.rb
@@ -14,6 +14,10 @@
 $VPATH = ["$(srcdir)", "$(srcdir)/#{tooldir.basename}", prismdir, tooldir]
 $INCFLAGS << " -I#{prismdir}"
 $CPPFLAGS = $CFLAGS = $INCFLAGS
+if $objext && $OBJEXT && $objext != $OBJEXT
+  ext1, ext2 = ".#{$objext}", ".#{$OBJEXT}"
+  objs.each {|obj| obj.chomp!(ext1) << ext2}
+end
 
 include FileUtils::Verbose
 mkpath(workdir)
@@ -22,16 +26,18 @@
   File.write('Makefile', [MakeMakefile.configuration(srcdir.to_s), <<~MAKEFILE].join(""))
     target = #{target}#{$EXEEXT}
     objs = #{objs.join(' ')}
+    Q =
+    .SUFFIXES: .c .#{$OBJEXT}
 
     $(target): $(objs)
-    \t#{link} $(objs)
+    \t$(Q) #{link} $(objs)
 
     objs: $(objs)
     .c.#{$OBJEXT}:
-    \t#{MakeMakefile::COMPILE_C}
+    \t$(Q) #{MakeMakefile::COMPILE_C}
 
     clean:
-    \t$(RM) $(target) $(objs) Makefile
-    \t$(RMDIRS) #{dirs.join(' ')}
+    \t$(Q) $(RM) $(target) $(objs) Makefile
+    \t$(Q) $(RMDIRS) #{dirs.join(' ')}
   MAKEFILE
 }