diff --git a/core/combo/arch/x86/x86.mk b/core/combo/arch/x86/x86.mk
index 73706c4099..f0704263b7 100644
--- a/core/combo/arch/x86/x86.mk
+++ b/core/combo/arch/x86/x86.mk
@@ -13,11 +13,7 @@ ARCH_X86_HAVE_MOVBE := false
 ARCH_X86_HAVE_POPCNT := false
 
 
-# XXX: This flag is probably redundant, because it should be set by default
-# by our toolchain binaries. However, there have been reports that this may
-# not always work as intended, so keep it unless we have the time to check
-# everything properly.
-
+# Some intrinsic functions used by libcxx only exist for prescott or newer CPUs.
 arch_variant_cflags := \
-    -march=i686 \
+    -march=prescott \