diff --git a/src/arch/x86_64/Makefile b/src/arch/x86_64/Makefile
index 246905cdb..b3064b752 100644
--- a/src/arch/x86_64/Makefile
+++ b/src/arch/x86_64/Makefile
@@ -13,6 +13,10 @@ CFLAGS		+= -m64
 ASFLAGS		+= --64
 LDFLAGS		+= -m elf_x86_64
 
+# Prevent use of MMX and SSE registers
+#
+CFLAGS		+= -mno-mmx -mno-sse
+
 # EFI requires -fshort-wchar, and nothing else currently uses wchar_t
 #
 CFLAGS		+= -fshort-wchar
diff --git a/src/arch/x86_64/include/bits/hyperv.h b/src/arch/x86_64/include/bits/hyperv.h
index 975b1eee0..fa8bb3f93 100644
--- a/src/arch/x86_64/include/bits/hyperv.h
+++ b/src/arch/x86_64/include/bits/hyperv.h
@@ -44,8 +44,7 @@ hv_call ( struct hv_hypervisor *hv, unsigned int code, const void *in,
 			       : "=a" ( result ), "+r" ( rcx ), "+r" ( rdx ),
 				 "+r" ( r8 )
 			       : "m" ( hypercall )
-			       : "r9", "r10", "r11", "xmm0", "xmm1", "xmm2",
-				 "xmm3", "xmm4", "xmm5" );
+			       : "r9", "r10", "r11" );
 	return result;
 }