diff --git a/src/alloy/backend/ivm/ivm_intcode.cc b/src/alloy/backend/ivm/ivm_intcode.cc
index 4aed60d15..61f6e0e0a 100644
--- a/src/alloy/backend/ivm/ivm_intcode.cc
+++ b/src/alloy/backend/ivm/ivm_intcode.cc
@@ -3792,6 +3792,8 @@ int Translate_PACK(TranslationContext& ctx, Instr* i) {
     IntCode_PACK_SHORT_2,
     IntCode_INVALID_TYPE,
     IntCode_INVALID_TYPE,
+    IntCode_INVALID_TYPE,
+    IntCode_INVALID_TYPE,
   };
   return DispatchToC(ctx, i, fns[i->flags]);
 }
@@ -3862,6 +3864,22 @@ uint32_t IntCode_UNPACK_S8_IN_16_HI(IntCodeState& ics, const IntCode* i) {
   }
   return IA_NEXT;
 }
+uint32_t IntCode_UNPACK_S16_IN_32_LO(IntCodeState& ics, const IntCode* i) {
+  const vec128_t& src1 = ics.rf[i->src1_reg].v128;
+  vec128_t& dest = ics.rf[i->dest_reg].v128;
+  for (int n = 0; n < 4; n++) {
+    dest.i4[n] = (int32_t)(int16_t)src1.s8[4 + n];
+  }
+  return IA_NEXT;
+}
+uint32_t IntCode_UNPACK_S16_IN_32_HI(IntCodeState& ics, const IntCode* i) {
+  const vec128_t& src1 = ics.rf[i->src1_reg].v128;
+  vec128_t& dest = ics.rf[i->dest_reg].v128;
+  for (int n = 0; n < 4; n++) {
+    dest.i4[n] = (int32_t)(int16_t)src1.s8[n];
+  }
+  return IA_NEXT;
+}
 int Translate_UNPACK(TranslationContext& ctx, Instr* i) {
   static IntCodeFn fns[] = {
     IntCode_UNPACK_D3DCOLOR,
@@ -3870,6 +3888,8 @@ int Translate_UNPACK(TranslationContext& ctx, Instr* i) {
     IntCode_UNPACK_SHORT_2,
     IntCode_UNPACK_S8_IN_16_LO,
     IntCode_UNPACK_S8_IN_16_HI,
+    IntCode_UNPACK_S16_IN_32_LO,
+    IntCode_UNPACK_S16_IN_32_HI,
   };
   return DispatchToC(ctx, i, fns[i->flags]);
 }
diff --git a/src/alloy/frontend/ppc/ppc_emit_altivec.cc b/src/alloy/frontend/ppc/ppc_emit_altivec.cc
index 9c6c9efa8..535f206a6 100644
--- a/src/alloy/frontend/ppc/ppc_emit_altivec.cc
+++ b/src/alloy/frontend/ppc/ppc_emit_altivec.cc
@@ -1702,7 +1702,7 @@ XEEMITTER(vupklpx,        0x100003CE, VX  )(PPCHIRBuilder& f, InstrData& i) {
 }
 
 int InstrEmit_vupkhsb_(PPCHIRBuilder& f, uint32_t vd, uint32_t vb) {
-  // bytes 0-7 expanded to halfwords 0-8 and sign extended
+  // bytes 0-7 expanded to halfwords 0-7 and sign extended
   Value* v = f.Unpack(f.LoadVR(vb), PACK_TYPE_S8_IN_16_HI);
   f.StoreVR(vd, v);
   return 0;
@@ -1714,15 +1714,8 @@ XEEMITTER(vupkhsb128,     VX128(6, 896),    VX128  )(PPCHIRBuilder& f, InstrData
   return InstrEmit_vupkhsb_(f, VX128_VD128, VX128_VB128);
 }
 
-int InstrEmit_vupkhsh_(PPCHIRBuilder& f, uint32_t vd, uint32_t va, uint32_t vb) {
-  return 1;
-}
-XEEMITTER(vupkhsh,        0x1000024E, VX  )(PPCHIRBuilder& f, InstrData& i) {
-  return InstrEmit_vupkhsh_(f, i.VX.VD, i.VX.VA, i.VX.VB);
-}
-
 int InstrEmit_vupklsb_(PPCHIRBuilder& f, uint32_t vd, uint32_t vb) {
-  // bytes 8-15 expanded to halfwords 0-8 and sign extended
+  // bytes 8-15 expanded to halfwords 0-7 and sign extended
   Value* v = f.Unpack(f.LoadVR(vb), PACK_TYPE_S8_IN_16_LO);
   f.StoreVR(vd, v);
   return 0;
@@ -1734,8 +1727,21 @@ XEEMITTER(vupklsb128,     VX128(6, 960),    VX128  )(PPCHIRBuilder& f, InstrData
   return InstrEmit_vupklsb_(f, VX128_VD128, VX128_VB128);
 }
 
+int InstrEmit_vupkhsh_(PPCHIRBuilder& f, uint32_t vd, uint32_t va, uint32_t vb) {
+  // halfwords 0-3 expanded to words 0-3 and sign extended
+  Value* v = f.Unpack(f.LoadVR(vb), PACK_TYPE_S16_IN_32_HI);
+  f.StoreVR(vd, v);
+  return 0;
+}
+XEEMITTER(vupkhsh,        0x1000024E, VX  )(PPCHIRBuilder& f, InstrData& i) {
+  return InstrEmit_vupkhsh_(f, i.VX.VD, i.VX.VA, i.VX.VB);
+}
+
 int InstrEmit_vupklsh_(PPCHIRBuilder& f, uint32_t vd, uint32_t va, uint32_t vb) {
-  return 1;
+  // halfwords 4-7 expanded to words 0-3 and sign extended
+  Value* v = f.Unpack(f.LoadVR(vb), PACK_TYPE_S16_IN_32_LO);
+  f.StoreVR(vd, v);
+  return 0;
 }
 XEEMITTER(vupklsh,        0x100002CE, VX  )(PPCHIRBuilder& f, InstrData& i) {
   return InstrEmit_vupklsh_(f, i.VX.VD, i.VX.VA, i.VX.VB);
diff --git a/src/alloy/hir/opcodes.h b/src/alloy/hir/opcodes.h
index af3c36b72..5fbbf198c 100644
--- a/src/alloy/hir/opcodes.h
+++ b/src/alloy/hir/opcodes.h
@@ -73,6 +73,8 @@ enum PackType {
   PACK_TYPE_SHORT_2 = 3,
   PACK_TYPE_S8_IN_16_LO = 4,
   PACK_TYPE_S8_IN_16_HI = 5,
+  PACK_TYPE_S16_IN_32_LO = 6,
+  PACK_TYPE_S16_IN_32_HI = 7,
 };