diff --git a/mingw-w64-tools-aarch64.patch b/mingw-w64-tools-aarch64.patch
new file mode 100644
index 0000000..adf1646
--- /dev/null
+++ b/mingw-w64-tools-aarch64.patch
@@ -0,0 +1,12 @@
+diff -rupN mingw-w64-v6.0.0/mingw-w64-tools/widl/include/windef.h mingw-w64-v6.0.0-new/mingw-w64-tools/widl/include/windef.h
+--- mingw-w64-v6.0.0/mingw-w64-tools/widl/include/windef.h	2018-09-14 16:16:43.000000000 +0200
++++ mingw-w64-v6.0.0-new/mingw-w64-tools/widl/include/windef.h	2019-06-04 17:41:05.156136224 +0200
+@@ -101,7 +101,7 @@ extern "C" {
+ #endif /* __cdecl */
+ 
+ #ifndef __ms_va_list
+-# if (defined(__x86_64__) || defined(__aarch64__)) && defined (__GNUC__)
++# if (defined(__x86_64__)) && defined (__GNUC__)
+ #  define __ms_va_list __builtin_ms_va_list
+ #  define __ms_va_start(list,arg) __builtin_ms_va_start(list,arg)
+ #  define __ms_va_end(list) __builtin_ms_va_end(list)
diff --git a/mingw-w64-tools.spec b/mingw-w64-tools.spec
index 06896f9..3dce4a7 100644
--- a/mingw-w64-tools.spec
+++ b/mingw-w64-tools.spec
@@ -29,6 +29,9 @@ Patch0:         mingw-w64-tools-2.0.999-s390.patch
 # https://bugzilla.redhat.com/show_bug.cgi?id=1047727
 Patch1:         mingw-w64-tools-widl-includedir.patch
 
+# aarch64 does not seem to know about __builtin_ms_va_list
+Patch2:         mingw-w64-tools-aarch64.patch
+
 BuildRequires:  gcc
 BuildRequires:  mingw32-filesystem >= 95
 BuildRequires:  mingw64-filesystem >= 95