diff --git a/lib/CMakeLists.txt b/lib/CMakeLists.txt
index a3bc372..e2166f3 100644
--- a/lib/CMakeLists.txt
+++ b/lib/CMakeLists.txt
@@ -156,6 +156,7 @@ set(GENERIC_SOURCES
   )
 
 set(x86_64_SOURCES
+  x86_64/chkstk.S
   x86_64/floatdidf.c
   x86_64/floatdisf.c
   x86_64/floatdixf.c
diff --git a/lib/x86_64/chkstk.S b/lib/x86_64/chkstk.S
new file mode 100644
index 0000000..186ef2c
--- /dev/null
+++ b/lib/x86_64/chkstk.S
@@ -0,0 +1,9 @@
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+
+#include "../assembly.h"
+
+.text
+.align 4
+DEFINE_COMPILERRT_FUNCTION(___chkstk_ms)
+	ret
