diff --git a/runtime/vm/intermediate_language.cc b/runtime/vm/intermediate_language.cc
index 036bf803769..e7d138f06c8 100644
--- a/runtime/vm/intermediate_language.cc
+++ b/runtime/vm/intermediate_language.cc
@@ -1202,6 +1202,10 @@ bool UnboxInt32Instr::CanDeoptimize() const {
     return !is_truncating() &&
         !RangeUtils::Fits(value()->definition()->range(),
                           RangeBoundary::kRangeBoundaryInt32);
+  } else if ((kSmiBits < 32) && value()->Type()->IsInt()) {
+    // Note: we don't support truncation of Bigint values.
+    return !RangeUtils::Fits(value()->definition()->range(),
+                             RangeBoundary::kRangeBoundaryInt32);
   } else {
     return true;
   }
diff --git a/runtime/vm/intermediate_language_arm.cc b/runtime/vm/intermediate_language_arm.cc
index c6f82c95a39..3bc55576fb8 100644
--- a/runtime/vm/intermediate_language_arm.cc
+++ b/runtime/vm/intermediate_language_arm.cc
@@ -3986,6 +3986,11 @@ void UnboxInteger32Instr::EmitNativeCode(FlowGraphCompiler* compiler) {
     __ SmiUntag(out, value);
   } else if (value_cid == kMintCid) {
     LoadInt32FromMint(compiler, value, out, temp, out_of_range);
+  } else if (!CanDeoptimize()) {
+    Label done;
+    __ SmiUntag(out, value, &done);
+    LoadInt32FromMint(compiler, value, out, kNoRegister, NULL);
+    __ Bind(&done);
   } else {
     Label done;
     __ SmiUntag(out, value, &done);
diff --git a/runtime/vm/intermediate_language_ia32.cc b/runtime/vm/intermediate_language_ia32.cc
index 76096c3a700..75b4d092362 100644
--- a/runtime/vm/intermediate_language_ia32.cc
+++ b/runtime/vm/intermediate_language_ia32.cc
@@ -3673,6 +3673,13 @@ void UnboxInteger32Instr::EmitNativeCode(FlowGraphCompiler* compiler) {
                       FieldAddress(value, hi_offset),
                       temp,
                       out_of_range);
+  } else if (!CanDeoptimize()) {
+    ASSERT(value == result);
+    Label done;
+    __ SmiUntag(value);
+    __ j(NOT_CARRY, &done);
+    __ movl(value, Address(value, TIMES_2, lo_offset));
+    __ Bind(&done);
   } else {
     ASSERT(value == result);
     Label done;
diff --git a/runtime/vm/intermediate_language_mips.cc b/runtime/vm/intermediate_language_mips.cc
index 1257aed0d75..ae1115d3a75 100644
--- a/runtime/vm/intermediate_language_mips.cc
+++ b/runtime/vm/intermediate_language_mips.cc
@@ -3347,6 +3347,13 @@ void UnboxInteger32Instr::EmitNativeCode(FlowGraphCompiler* compiler) {
     __ SmiUntag(out, value);
   } else if (value_cid == kMintCid) {
     LoadInt32FromMint(compiler, value, out, out_of_range);
+  } else if (!CanDeoptimize()) {
+    Label done;
+    __ SmiUntag(out, value);
+    __ andi(CMPRES1, value, Immediate(kSmiTagMask));
+    __ beq(CMPRES1, ZR, &done);
+    LoadInt32FromMint(compiler, value, out, NULL);
+    __ Bind(&done);
   } else {
     Label done;
     __ SmiUntag(out, value);