diff --git a/tslang/lib/TypeScript/MLIRGenImpl.h b/tslang/lib/TypeScript/MLIRGenImpl.h
index c4b942158..18fbb081c 100644
--- a/tslang/lib/TypeScript/MLIRGenImpl.h
+++ b/tslang/lib/TypeScript/MLIRGenImpl.h
@@ -6630,10 +6630,12 @@ class MLIRGenImpl
             // 64-bit integer types - a rung of the promotion ladder - not a size or a pointer. The
             // getIndexType() beside them is a different thing entirely and IS target-dependent; it
             // sits at this rung because that is where it promotes, not because it is 64 bits wide.
-            getNumberType(), builder.getF64Type(), builder.getI64Type(), SInt(64), builder.getIndexType(),
-            builder.getF32Type(), SInt(32), builder.getI32Type(),
-            builder.getF16Type(), SInt(16), builder.getI16Type(),
-            SInt(8), builder.getI8Type()
+            // An unsigned type follows the signed and signless ones of its width. Missing from the
+            // ladder, `u64 * 2` found only the literal's s32 and multiplied in 32 bits.
+            getNumberType(), builder.getF64Type(), builder.getI64Type(), SInt(64), UInt(64), builder.getIndexType(),
+            builder.getF32Type(), SInt(32), builder.getI32Type(), UInt(32),
+            builder.getF16Type(), SInt(16), builder.getI16Type(), UInt(16),
+            SInt(8), builder.getI8Type(), UInt(8)
         };
     }
 
@@ -6689,6 +6691,11 @@ class MLIRGenImpl
         return mlir::IntegerType::get(builder.getContext(), width, mlir::IntegerType::Signed);
     }
 
+    mlir::Type UInt(int width)
+    {
+        return mlir::IntegerType::get(builder.getContext(), width, mlir::IntegerType::Unsigned);
+    }
+
     // JS/TS `===`/`!==` never coerce: operands of clearly different primitive kinds
     // (boolean vs number, boolean vs string, string vs number) are simply unequal,
     // full stop. Everything downstream of this function (adjustTypesForBinaryOp's
diff --git a/tslang/test/tester/CMakeLists.txt b/tslang/test/tester/CMakeLists.txt
index 891d8b56e..29e28da30 100644
--- a/tslang/test/tester/CMakeLists.txt
+++ b/tslang/test/tester/CMakeLists.txt
@@ -272,6 +272,7 @@ tslang_add_test(NAME test-compile-00-numbers COMMAND test-runner "${PROJECT_SOUR
 tslang_add_test(NAME test-compile-00-equals COMMAND test-runner "${PROJECT_SOURCE_DIR}/test/tester/tests/00equals.ts")
 tslang_add_test(NAME test-compile-00-bool-arith-ops COMMAND test-runner "${PROJECT_SOURCE_DIR}/test/tester/tests/00bool_arith_ops.ts")
 tslang_add_test(NAME test-compile-00-int64-shift-bitwise COMMAND test-runner "${PROJECT_SOURCE_DIR}/test/tester/tests/00int64_shift_bitwise.ts")
+tslang_add_test(NAME test-compile-00-int64-mul-literal COMMAND test-runner "${PROJECT_SOURCE_DIR}/test/tester/tests/00int64_mul_literal.ts")
 tslang_add_test(NAME test-compile-00-literal-union-arith COMMAND test-runner "${PROJECT_SOURCE_DIR}/test/tester/tests/00literal_union_arith.ts")
 tslang_add_test(NAME test-compile-00-bool-const-array COMMAND test-runner "${PROJECT_SOURCE_DIR}/test/tester/tests/00bool_const_array.ts")
 tslang_add_test(NAME test-compile-00-mixed-type-ops COMMAND test-runner "${PROJECT_SOURCE_DIR}/test/tester/tests/00mixed_type_ops.ts")
@@ -807,6 +808,7 @@ tslang_add_test(NAME test-jit-00-numbers COMMAND test-runner -jit "${PROJECT_SOU
 tslang_add_test(NAME test-jit-00-equals COMMAND test-runner -jit "${PROJECT_SOURCE_DIR}/test/tester/tests/00equals.ts")
 tslang_add_test(NAME test-jit-00-bool-arith-ops COMMAND test-runner -jit "${PROJECT_SOURCE_DIR}/test/tester/tests/00bool_arith_ops.ts")
 tslang_add_test(NAME test-jit-00-int64-shift-bitwise COMMAND test-runner -jit "${PROJECT_SOURCE_DIR}/test/tester/tests/00int64_shift_bitwise.ts")
+tslang_add_test(NAME test-jit-00-int64-mul-literal COMMAND test-runner -jit "${PROJECT_SOURCE_DIR}/test/tester/tests/00int64_mul_literal.ts")
 tslang_add_test(NAME test-jit-00-literal-union-arith COMMAND test-runner -jit "${PROJECT_SOURCE_DIR}/test/tester/tests/00literal_union_arith.ts")
 tslang_add_test(NAME test-jit-00-bool-const-array COMMAND test-runner -jit "${PROJECT_SOURCE_DIR}/test/tester/tests/00bool_const_array.ts")
 tslang_add_test(NAME test-jit-00-mixed-type-ops COMMAND test-runner -jit "${PROJECT_SOURCE_DIR}/test/tester/tests/00mixed_type_ops.ts")
@@ -1798,6 +1800,7 @@ set(TSLANG_CORPUS
     00async_result_types.ts
     00bool_arith_ops.ts
     00int64_shift_bitwise.ts
+    00int64_mul_literal.ts
     00literal_union_arith.ts
     00bool_const_array.ts
     00break_continue_scope_exit.ts
diff --git a/tslang/test/tester/tests/00int64_mul_literal.ts b/tslang/test/tester/tests/00int64_mul_literal.ts
new file mode 100644
index 000000000..7a18f2ae5
--- /dev/null
+++ b/tslang/test/tester/tests/00int64_mul_literal.ts
@@ -0,0 +1,41 @@
+// regression test: arithmetic of a 64-bit unsigned integer and an integer literal is done in 64 bits.
+//
+// bug found and fixed: the numeric promotion ladder had no unsigned types, so `u64 * 2` found only
+// the literal's s32 and multiplied in 32 bits: `2^32 * 2` was 0, and `d *= 256` wrapped to 0 after
+// four bytes.
+
+function main() {
+    const twoTo32: u64 = 4294967296;
+    const twoTo33: u64 = 8589934592;
+    const twoTo32Plus2: u64 = 4294967298;
+    const twoTo32Minus2: u64 = 4294967294;
+
+    let a: u64 = 4294967296;
+    assert(a * 2 == twoTo33);
+    assert(2 * a == twoTo33);
+    assert(a + 2 == twoTo32Plus2);
+    assert(a - 2 == twoTo32Minus2);
+
+    let d: u64 = 16777216;
+    d *= 256;
+    assert(d == twoTo32);
+
+    // the shape the bug was found in: a std::string's word built a byte at a time
+    let word: u64 = 0;
+    let shift: u64 = 1;
+    const bytes = [109, 97, 105, 110, 95, 118, 115];
+    for (const b of bytes) {
+        const byte: u64 = b;
+        word += byte * shift;
+        shift *= 256;
+    }
+
+    const mainVs: u64 = 32499774568096109;
+    assert(word == mainVs);
+
+    const k: u64 = 256;
+    let e: u64 = 16777216;
+    assert(e * k == twoTo32);
+
+    print("done.");
+}