diff --git a/src/alloy/backend/x64/x64_emitter.cc b/src/alloy/backend/x64/x64_emitter.cc
index 204d614cc..2a7a933d3 100644
--- a/src/alloy/backend/x64/x64_emitter.cc
+++ b/src/alloy/backend/x64/x64_emitter.cc
@@ -790,6 +790,8 @@ Address X64Emitter::GetXmmConstPtr(XmmConst id) {
       /* XMMZero                */ vec128f(0.0f),
       /* XMMOne                 */ vec128f(1.0f),
       /* XMMNegativeOne         */ vec128f(-1.0f, -1.0f, -1.0f, -1.0f),
+      /* XMMFFFF                */ vec128i(0xFFFFFFFFu, 0xFFFFFFFFu,
+                                           0xFFFFFFFFu, 0xFFFFFFFFu),
       /* XMMMaskX16Y16          */ vec128i(0x0000FFFFu, 0xFFFF0000u,
                                            0x00000000u, 0x00000000u),
       /* XMMFlipX16Y16          */ vec128i(0x00008000u, 0x00000000u,
diff --git a/src/alloy/backend/x64/x64_emitter.h b/src/alloy/backend/x64/x64_emitter.h
index 009f72e92..83b2bd4ff 100644
--- a/src/alloy/backend/x64/x64_emitter.h
+++ b/src/alloy/backend/x64/x64_emitter.h
@@ -42,6 +42,7 @@ enum XmmConst {
   XMMZero = 0,
   XMMOne,
   XMMNegativeOne,
+  XMMFFFF,
   XMMMaskX16Y16,
   XMMFlipX16Y16,
   XMMFixX16Y16,
diff --git a/src/alloy/backend/x64/x64_sequences.cc b/src/alloy/backend/x64/x64_sequences.cc
index 4bf74ead2..acc2242a8 100644
--- a/src/alloy/backend/x64/x64_sequences.cc
+++ b/src/alloy/backend/x64/x64_sequences.cc
@@ -4109,7 +4109,7 @@ EMITTER(NOT_I64, MATCH(I<OPCODE_NOT, I64<>, I64<>>)) {
 EMITTER(NOT_V128, MATCH(I<OPCODE_NOT, V128<>, V128<>>)) {
   static void Emit(X64Emitter& e, const EmitArgType& i) {
     // dest = src ^ 0xFFFF...
-    e.vpxor(i.dest, i.src1, e.GetXmmConstPtr(XMMAbsMaskPD /* FF... */));
+    e.vpxor(i.dest, i.src1, e.GetXmmConstPtr(XMMFFFF /* FF... */));
   }
 };
 EMITTER_OPCODE_TABLE(
diff --git a/src/alloy/frontend/ppc/ppc_hir_builder.cc b/src/alloy/frontend/ppc/ppc_hir_builder.cc
index 4168d92a9..cb3722883 100644
--- a/src/alloy/frontend/ppc/ppc_hir_builder.cc
+++ b/src/alloy/frontend/ppc/ppc_hir_builder.cc
@@ -301,6 +301,8 @@ void PPCHIRBuilder::UpdateCR6(Value* src_value) {
   // Testing for all 1's and all 0's.
   // if (Rc) CR6 = all_equal | 0 | none_equal | 0
   // TODO(benvanik): efficient instruction?
+  StoreContext(offsetof(PPCContext, cr6.cr6_0), LoadZero(INT8_TYPE));
+  StoreContext(offsetof(PPCContext, cr6.cr6_2), LoadZero(INT8_TYPE));
   StoreContext(offsetof(PPCContext, cr6.cr6_all_equal),
                IsFalse(Not(src_value)));
   StoreContext(offsetof(PPCContext, cr6.cr6_none_equal), IsFalse(src_value));