diff --git a/src/Make_ming.mak b/src/Make_ming.mak
index 695b7e7..b8d7b20 100644
--- a/src/Make_ming.mak
+++ b/src/Make_ming.mak
@@ -288,18 +288,26 @@
 ifneq ($(wildcard $(RUBY)/lib/ruby/$(RUBY_VER_LONG)/i386-mingw32),)
 RUBY_PLATFORM = i386-mingw32
 else
+ifneq ($(wildcard $(RUBY)/lib/ruby/$(RUBY_VER_LONG)/x64-mingw32),)
+RUBY_PLATFORM = x64-mingw32
+else
 RUBY_PLATFORM = i386-mswin32
 endif
 endif
 endif
+endif
 
 ifndef RUBY_INSTALL_NAME
 ifeq ($(RUBY_VER), 16)
 RUBY_INSTALL_NAME = mswin32-ruby$(RUBY_API_VER)
 else
+ifeq ($(ARCH),x86-64)
+RUBY_INSTALL_NAME = x64-msvcrt-ruby$(RUBY_API_VER)
+else
 RUBY_INSTALL_NAME = msvcrt-ruby$(RUBY_API_VER)
 endif
 endif
+endif
 
 ifeq (19, $(word 1,$(sort 19 $(RUBY_VER))))
 RUBY_19_OR_LATER = 1