Index: src/libcfa/concurrency/CtxSwitch-x86_64.S
===================================================================
--- src/libcfa/concurrency/CtxSwitch-x86_64.S	(revision eb2e723e2366bc9652cf9888645a9249f5fd129a)
+++ src/libcfa/concurrency/CtxSwitch-x86_64.S	(revision ee897e4b569553fa2a4e77d3de048d5fbfcba4fb)
@@ -49,4 +49,7 @@
 	// Save volatile registers on the stack.
 
+	subq   $8,%rsp
+	stmxcsr 0(%rsp)         // 4 bytes
+	fnstcw  4(%rsp)         // 2 bytes
 	pushq %r15
 	pushq %r14
@@ -72,4 +75,7 @@
 	popq %r14
 	popq %r15
+	fldcw   4(%rsp)
+	ldmxcsr 0(%rsp)
+	addq $8,%rsp
 
 	// Return to thread.