diff --git a/src/arch/x86.rs b/src/arch/x86.rs
index 22b03a5..1b3c449 100644
--- a/src/arch/x86.rs
+++ b/src/arch/x86.rs
@@ -154,9 +154,9 @@ pub unsafe fn swap(arg: usize, old_sp: *mut StackPointer, new_sp: *const StackPo
       "{edx}" (new_sp)
       "{edi}" (new_cfa)
     :/*"eax",*/"ebx", "ecx",  "edx",  "esi",  "edi",/*"ebp",  "esp",*/
-      "mmx0", "mmx1", "mmx2", "mmx3", "mmx4", "mmx5", "mmx6", "mmx7",
+      "mm0",  "mm1",  "mm2",  "mm3",  "mm4",  "mm5",  "mm6",  "mm7",
       "xmm0", "xmm1", "xmm2", "xmm3", "xmm4", "xmm5", "xmm6", "xmm7",
-      "cc", "fpsr", "flags", "memory"
+      "cc", "dirflag", "fpsr", "flags", "memory"
     : "volatile");
   ret
 }
diff --git a/src/arch/x86_64.rs b/src/arch/x86_64.rs
index d6b46af..a3d30d7 100644
--- a/src/arch/x86_64.rs
+++ b/src/arch/x86_64.rs
@@ -182,11 +182,12 @@ pub unsafe fn swap(arg: usize, old_sp: *mut StackPointer, new_sp: *const StackPo
       "{rcx}" (new_cfa)
     : "rax",   "rbx",   "rcx",   "rdx",   "rsi", /*"rdi",   "rbp",   "rsp",*/
       "r8",    "r9",    "r10",   "r11",   "r12",   "r13",   "r14",   "r15",
+      "mm0",   "mm1",   "mm2",   "mm3",   "mm4",   "mm5",   "mm6",   "mm7",
       "xmm0",  "xmm1",  "xmm2",  "xmm3",  "xmm4",  "xmm5",  "xmm6",  "xmm7",
       "xmm8",  "xmm9",  "xmm10", "xmm11", "xmm12", "xmm13", "xmm14", "xmm15",
       "xmm16", "xmm17", "xmm18", "xmm19", "xmm20", "xmm21", "xmm22", "xmm23",
-      "xmm24", "xmm25", "xmm26", "xmm27", "xmm28", "xmm29", "xmm30", "xmm31"
-      "cc", "fpsr", "flags", "memory"
+      "xmm24", "xmm25", "xmm26", "xmm27", "xmm28", "xmm29", "xmm30", "xmm31",
+      "cc", "dirflag", "fpsr", "flags", "memory"
       // Ideally, we would set the LLVM "noredzone" attribute on this function
       // (and it would be propagated to the call site). Unfortunately, rustc
       // provides no such functionality. Fortunately, by a lucky coincidence,