diff --git a/libserialport.h b/libserialport.h
index 7467f74..e886fd2 100644
--- a/libserialport.h
+++ b/libserialport.h
@@ -280,20 +280,32 @@ extern "C" {
 
 /** @cond */
 #ifdef _MSC_VER
-/* Microsoft Visual C/C++ compiler in use */
-#ifdef LIBSERIALPORT_MSBUILD
-/* Building the library - need to export DLL symbols */
-#define SP_API __declspec(dllexport)
+	/* Microsoft Visual C/C++ compiler in use */
+	#ifdef LIBSERIALPORT_MSBUILD
+		// Building the library - need to export DLL symbols
+		#define SP_API __declspec(dllexport)
+	#else
+		// Using the library - need to import DLL symbols
+		#define SP_API __declspec(dllimport)
+	#endif
+	// #define SP_CALL
+#elif defined(__MINGW32__)
+	// You should define LIBSERIALPORT_MINGW64BUILD *only* when building the DLL.
+	#ifdef LIBSERIALPORT_MINGW64BUILD
+		#define SP_API __declspec(dllexport)
+	#else
+		#define SP_API __declspec(dllimport)
+	#endif
+	// Define calling convention in one place, for convenience.
+	// On MinGW64 "__cdecl" is default value.
+	// #define SP_CALL __cdecl
 #else
-/* Using the library - need to import DLL symbols */
-#define SP_API __declspec(dllimport)
-#endif
-#else
-/* Some other compiler in use */
-#ifndef LIBSERIALPORT_ATBUILD
-/* Not building the library itself - don't need any special prefixes. */
-#define SP_API
-#endif
+	/* Some other compiler in use */
+	#ifndef LIBSERIALPORT_ATBUILD
+		/* Not building the library itself - don't need any special prefixes. */
+		#define SP_API
+	#endif
+	// #define SP_CALL
 #endif
 /** @endcond */
 
diff --git a/libserialport_internal.h b/libserialport_internal.h
index ecf8fe9..a66f103 100644
--- a/libserialport_internal.h
+++ b/libserialport_internal.h
@@ -47,6 +47,16 @@
 #define SP_PRIV
 #endif
 
+#ifdef LIBSERIALPORT_MINGW64BUILD
+/* If building with MinGW64 tools, define necessary things that
+   would otherwise appear in config.h. */
+#define SP_PRIV
+#endif
+
+#ifndef SP_PRIV
+#error "You should define one of LIBSERIALPORT_ATBUILD, LIBSERIALPORT_MSBUILD, LIBSERIALPORT_MINGW64BUILD"
+#endif
+
 #include "libserialport.h"
 
 #include <string.h>
diff --git a/mingw64.mak b/mingw64.mak
new file mode 100644
index 0000000..445b1b1
--- /dev/null
+++ b/mingw64.mak
@@ -0,0 +1,53 @@
+# mingw64.mak: build libserialport.dll using MinGW64-w64
+
+# Program for compiling C programs
+CC = gcc
+
+# Extra flags to give to the C preprocessor
+CPPFLAGS =
+CPPFLAGS += -DLIBSERIALPORT_MINGW64BUILD
+# CPPFLAGS += -DLIBSERIALPORT_MSBUILD
+# CPPFLAGS += -DLIBSERIALPORT_ATBUILD
+# CPPFLAGS += -DHAVE_CONFIG_H
+
+# Extra flags to give to the C compiler.
+CFLAGS =
+CFLAGS += -I. -std=c99
+CFLAGS += -Wall -Wextra -pedantic -Wmissing-prototypes -Wshadow
+CFLAGS += -g -O2
+
+# Extra flags when invoking the linker
+LDFLAGS = -s -shared -Wl,--subsystem,windows
+
+# Library flags or names when invoking the linker
+LDLIBS = -lsetupapi
+
+# Command to remove a file
+RM = rm -f
+
+H_FILES = libserialport_internal.h libserialport.h
+O_FILES = serialport.o timing.o windows.o
+
+all: libserialport.dll
+
+libserialport.dll: $(O_FILES)
+	gcc -o libserialport.dll $(O_FILES) $(LDFLAGS) $(LDLIBS)
+
+serialport.o: serialport.c $(H_FILES)
+	$(CC) -c $(CPPFLAGS) $(CFLAGS) -o $@ $<
+
+timing.o: timing.c $(H_FILES)
+	$(CC) -c $(CPPFLAGS) $(CFLAGS) -o $@ $<
+
+windows.o: windows.c $(H_FILES)
+	$(CC) -c $(CPPFLAGS) $(CFLAGS) -o $@ $<
+
+install:
+	@echo "install is not yet implemented"
+	exit 1
+
+clean:
+	$(RM) libserialport.dll
+	$(RM) *.o
+
+.PHONY: all install clean