--- a/configure.ac
+++ b/configure.ac
@@ -1361,7 +1361,7 @@
 AC_CHECK_HEADERS(sys/event.h)
 AC_CHECK_HEADERS(stdatomic.h)
 
-AS_CASE("$target_cpu", [x64|x86_64|i[3-6]86*], [
+AS_CASE("$target_cpu", [x64|x86_64|[i[3-6]86*]], [
   AC_CHECK_HEADERS(x86intrin.h)
 ])
 RUBY_UNIVERSAL_CHECK_HEADER([x86_64, i386], x86intrin.h)
@@ -3499,7 +3499,7 @@
 	    ],
 	    [mingw*], [
 		RUBY_SO_NAME="${rb_cv_msvcrt}"'-$(RUBY_BASE_NAME)$(MAJOR)$(MINOR)0'
-		AS_IF([test x"${target_cpu}" != xi386], [
+		AS_IF([test x"${target_cpu}" != xi386 || test x"${rb_cv_msvcrt}" != xmsvcrt], [
 		    RUBY_SO_NAME="${target_cpu}-${RUBY_SO_NAME}"
 		])
 	    ],
@@ -4070,6 +4070,7 @@
 	[mingw*], [
 	    AS_IF([test x"$enable_shared" = xyes], [
 		LIBRUBY_SO='$(RUBY_SO_NAME)'.dll
+		LIBRUBY_SONAME=''
 		LIBRUBY_DLDFLAGS="${LIBRUBY_DLDFLAGS}"' $(RUBYDEF)'
 	    ])
 	    EXPORT_PREFIX=' '