diff --git a/mingw-w64-v9.0.0-strnlen_s.patch b/mingw-w64-v9.0.0-strnlen_s.patch
new file mode 100644
index 0000000..01cdfca
--- /dev/null
+++ b/mingw-w64-v9.0.0-strnlen_s.patch
@@ -0,0 +1,14 @@
+--- mingw-w64-v9.0.0/mingw-w64-headers/crt/sec_api/string_s.h	2021-05-22 14:34:25.000000000 +0200
++++ mingw-w64-v9.0.0/mingw-w64-headers/crt/sec_api/string_s.h	2021-07-08 09:10:48.082143084 +0200
+@@ -43,9 +43,11 @@
+   _CRTIMP errno_t __cdecl strcat_s(char *_Dst, rsize_t _SizeInBytes, const char * _Src);
+   __DEFINE_CPP_OVERLOAD_SECURE_FUNC_0_1(errno_t, strcat_s, char, _Dest, const char *, _Source)
+ 
++#ifdef _NEEDS_STRNLEN_S
+   __forceinline size_t __cdecl strnlen_s(const char * _src, size_t _count) {
+     return _src ? strnlen(_src, _count) : 0;
+   }
++#endif
+ 
+   _SECIMP errno_t __cdecl memmove_s(void *_dest,size_t _numberOfElements,const void *_src,size_t _count);
+ #ifndef _WSTRING_S_DEFINED
diff --git a/mingw32-headers.changes b/mingw32-headers.changes
index 519561f..136e17e 100644
--- a/mingw32-headers.changes
+++ b/mingw32-headers.changes
@@ -1,3 +1,12 @@
+-------------------------------------------------------------------
+Thu Jul  8 07:13:22 UTC 2021 - Fridrich Strba <fstrba@suse.com>
+
+- Added patch:
+  * mingw-w64-v9.0.0-strnlen_s.patch
+    + work around the "multiple definition of `strnlen_s'" error
+    + the function still accessible by defining _NEEDS_STRNLEN_S
+      before inclusion of the header
+
 -------------------------------------------------------------------
 Fri Jul  2 12:34:00 UTC 2021 - Jan Engelhardt <jengelh@inai.de>
 
diff --git a/mingw32-headers.spec b/mingw32-headers.spec
index 2d4d2a5..7abc7aa 100644
--- a/mingw32-headers.spec
+++ b/mingw32-headers.spec
@@ -25,6 +25,7 @@ Group:          Development/Libraries/C and C++
 URL:            http://mingw-w64.sf.net/
 Source:         http://downloads.sf.net/mingw-w64/mingw-w64-v%{version}.tar.bz2
 Source1000:     %name-rpmlintrc
+Patch0:         mingw-w64-v9.0.0-strnlen_s.patch
 BuildRequires:  mingw32-filesystem
 BuildRequires:  xz
 #!BuildIgnore:	post-build-checks
@@ -49,7 +50,7 @@ and only exist to satisfy dependencies in MinGW's unistd.h until
 an actual pthread implementation (like winpthreads) is installed.
 
 %prep
-%autosetup -n mingw-w64-v%version/mingw-w64-headers
+%autosetup -n mingw-w64-v%version/mingw-w64-headers -p2
 
 %build
 %_mingw32_configure \