diff --git a/libc/src/__support/UInt.h b/libc/src/__support/UInt.h
--- a/libc/src/__support/UInt.h
+++ b/libc/src/__support/UInt.h
@@ -137,7 +137,7 @@
   constexpr uint64_t add(const BigInt<Bits, Signed> &x) {
     SumCarry<uint64_t> s{0, 0};
     for (size_t i = 0; i < WORDCOUNT; ++i) {
-      s = add_with_carry(val[i], x.val[i], s.carry);
+      s = add_with_carry_const(val[i], x.val[i], s.carry);
       val[i] = s.sum;
     }
     return s.carry;
@@ -176,7 +176,7 @@
   constexpr uint64_t sub(const BigInt<Bits, Signed> &x) {
     DiffBorrow<uint64_t> d{0, 0};
     for (size_t i = 0; i < WORDCOUNT; ++i) {
-      d = sub_with_borrow(val[i], x.val[i], d.borrow);
+      d = sub_with_borrow_const(val[i], x.val[i], d.borrow);
       val[i] = d.diff;
     }
     return d.borrow;
diff --git a/libc/test/src/math/FmaTest.h b/libc/test/src/math/FmaTest.h
--- a/libc/test/src/math/FmaTest.h
+++ b/libc/test/src/math/FmaTest.h
@@ -69,7 +69,8 @@
   void test_subnormal_range(Func func) {
     constexpr UIntType COUNT = 100'001;
     constexpr UIntType STEP =
-        (FPBits::MAX_SUBNORMAL - FPBits::MIN_SUBNORMAL) / COUNT;
+        (UIntType(FPBits::MAX_SUBNORMAL) - UIntType(FPBits::MIN_SUBNORMAL)) /
+        COUNT;
     for (UIntType v = FPBits::MIN_SUBNORMAL, w = FPBits::MAX_SUBNORMAL;
          v <= FPBits::MAX_SUBNORMAL && w >= FPBits::MIN_SUBNORMAL;
          v += STEP, w -= STEP) {
@@ -83,7 +84,8 @@
 
   void test_normal_range(Func func) {
     constexpr UIntType COUNT = 100'001;
-    constexpr UIntType STEP = (FPBits::MAX_NORMAL - FPBits::MIN_NORMAL) / COUNT;
+    constexpr UIntType STEP =
+        (UIntType(FPBits::MAX_NORMAL) - UIntType(FPBits::MIN_NORMAL)) / COUNT;
     for (UIntType v = FPBits::MIN_NORMAL, w = FPBits::MAX_NORMAL;
          v <= FPBits::MAX_NORMAL && w >= FPBits::MIN_NORMAL;
          v += STEP, w -= STEP) {
diff --git a/libc/test/src/math/HypotTest.h b/libc/test/src/math/HypotTest.h
--- a/libc/test/src/math/HypotTest.h
+++ b/libc/test/src/math/HypotTest.h
@@ -85,7 +85,8 @@
 
   void test_normal_range(Func func) {
     constexpr UIntType COUNT = 10'001;
-    constexpr UIntType STEP = (FPBits::MAX_NORMAL - FPBits::MIN_NORMAL) / COUNT;
+    constexpr UIntType STEP =
+        (UIntType(FPBits::MAX_NORMAL) - UIntType(FPBits::MIN_NORMAL)) / COUNT;
     for (int signs = 0; signs < 4; ++signs) {
       for (UIntType v = FPBits::MIN_NORMAL, w = FPBits::MAX_NORMAL;
            v <= FPBits::MAX_NORMAL && w >= FPBits::MIN_NORMAL;
diff --git a/libc/test/src/math/ILogbTest.h b/libc/test/src/math/ILogbTest.h
--- a/libc/test/src/math/ILogbTest.h
+++ b/libc/test/src/math/ILogbTest.h
@@ -79,7 +79,8 @@
     using UIntType = typename FPBits::UIntType;
     constexpr UIntType COUNT = 10'001;
     constexpr UIntType STEP =
-        (FPBits::MAX_SUBNORMAL - FPBits::MIN_SUBNORMAL) / COUNT;
+        (UIntType(FPBits::MAX_SUBNORMAL) - UIntType(FPBits::MIN_SUBNORMAL)) /
+        COUNT;
     for (UIntType v = FPBits::MIN_SUBNORMAL; v <= FPBits::MAX_SUBNORMAL;
          v += STEP) {
       T x = T(FPBits(v));
@@ -97,7 +98,8 @@
     using FPBits = __llvm_libc::fputil::FPBits<T>;
     using UIntType = typename FPBits::UIntType;
     constexpr UIntType COUNT = 10'001;
-    constexpr UIntType STEP = (FPBits::MAX_NORMAL - FPBits::MIN_NORMAL) / COUNT;
+    constexpr UIntType STEP =
+        (UIntType(FPBits::MAX_NORMAL) - UIntType(FPBits::MIN_NORMAL)) / COUNT;
     for (UIntType v = FPBits::MIN_NORMAL; v <= FPBits::MAX_NORMAL; v += STEP) {
       T x = T(FPBits(v));
       if (isnan(x) || isinf(x) || x == 0.0)
diff --git a/libc/test/src/math/LdExpTest.h b/libc/test/src/math/LdExpTest.h
--- a/libc/test/src/math/LdExpTest.h
+++ b/libc/test/src/math/LdExpTest.h
@@ -70,7 +70,7 @@
   void testUnderflowToZeroOnNormal(LdExpFunc func) {
     // In this test, we pass a normal nubmer to func and expect zero
     // to be returned due to underflow.
-    int32_t base_exponent = FPBits::EXPONENT_BIAS + MANTISSA_WIDTH;
+    int32_t base_exponent = FPBits::EXPONENT_BIAS + int32_t(MANTISSA_WIDTH);
     int32_t exp_array[] = {base_exponent + 5, base_exponent + 4,
                            base_exponent + 3, base_exponent + 2,
                            base_exponent + 1};
@@ -83,7 +83,7 @@
   void testUnderflowToZeroOnSubnormal(LdExpFunc func) {
     // In this test, we pass a normal nubmer to func and expect zero
     // to be returned due to underflow.
-    int32_t base_exponent = FPBits::EXPONENT_BIAS + MANTISSA_WIDTH;
+    int32_t base_exponent = FPBits::EXPONENT_BIAS + int32_t(MANTISSA_WIDTH);
     int32_t exp_array[] = {base_exponent + 5, base_exponent + 4,
                            base_exponent + 3, base_exponent + 2,
                            base_exponent + 1};
@@ -105,13 +105,22 @@
       for (T x : val_array) {
         // We compare the result of ldexp with the result
         // of the native multiplication/division instruction.
-        ASSERT_FP_EQ(func(x, exp), x * (UIntType(1) << exp));
-        ASSERT_FP_EQ(func(x, -exp), x / (UIntType(1) << exp));
+
+        // We need to use a NormalFloat here (instead of 1 << exp), because
+        // there are 32 bit systems that don't support 128bit long ints but
+        // support long doubles. This test can do 1 << 64, which would fail
+        // in these systems.
+        NormalFloat two_to_exp = NormalFloat(static_cast<T>(1.L));
+        two_to_exp = two_to_exp.mul2(exp);
+
+        ASSERT_FP_EQ(func(x, exp), x * two_to_exp);
+        ASSERT_FP_EQ(func(x, -exp), x / two_to_exp);
       }
     }
 
     // Normal which trigger mantissa overflow.
-    T x = NormalFloat(-FPBits::EXPONENT_BIAS + 1, 2 * NormalFloat::ONE - 1, 0);
+    T x = NormalFloat(-FPBits::EXPONENT_BIAS + 1,
+                      UIntType(2) * NormalFloat::ONE - UIntType(1), 0);
     ASSERT_FP_EQ(func(x, -1), x / 2);
     ASSERT_FP_EQ(func(-x, -1), -x / 2);
 
diff --git a/libc/test/src/math/RIntTest.h b/libc/test/src/math/RIntTest.h
--- a/libc/test/src/math/RIntTest.h
+++ b/libc/test/src/math/RIntTest.h
@@ -95,7 +95,8 @@
   void testSubnormalRange(RIntFunc func) {
     constexpr UIntType COUNT = 100'001;
     constexpr UIntType STEP =
-        (FPBits::MAX_SUBNORMAL - FPBits::MIN_SUBNORMAL) / COUNT;
+        (UIntType(FPBits::MAX_SUBNORMAL) - UIntType(FPBits::MIN_SUBNORMAL)) /
+        COUNT;
     for (UIntType i = FPBits::MIN_SUBNORMAL; i <= FPBits::MAX_SUBNORMAL;
          i += STEP) {
       T x = T(FPBits(i));
@@ -109,7 +110,8 @@
 
   void testNormalRange(RIntFunc func) {
     constexpr UIntType COUNT = 100'001;
-    constexpr UIntType STEP = (FPBits::MAX_NORMAL - FPBits::MIN_NORMAL) / COUNT;
+    constexpr UIntType STEP =
+        (UIntType(FPBits::MAX_NORMAL) - UIntType(FPBits::MIN_NORMAL)) / COUNT;
     for (UIntType i = FPBits::MIN_NORMAL; i <= FPBits::MAX_NORMAL; i += STEP) {
       T x = T(FPBits(i));
       // In normal range on x86 platforms, the long double implicit 1 bit can be
diff --git a/libc/test/src/math/RemQuoTest.h b/libc/test/src/math/RemQuoTest.h
--- a/libc/test/src/math/RemQuoTest.h
+++ b/libc/test/src/math/RemQuoTest.h
@@ -97,7 +97,8 @@
   void testSubnormalRange(RemQuoFunc func) {
     constexpr UIntType COUNT = 100'001;
     constexpr UIntType STEP =
-        (FPBits::MAX_SUBNORMAL - FPBits::MIN_SUBNORMAL) / COUNT;
+        (UIntType(FPBits::MAX_SUBNORMAL) - UIntType(FPBits::MIN_SUBNORMAL)) /
+        COUNT;
     for (UIntType v = FPBits::MIN_SUBNORMAL, w = FPBits::MAX_SUBNORMAL;
          v <= FPBits::MAX_SUBNORMAL && w >= FPBits::MIN_SUBNORMAL;
          v += STEP, w -= STEP) {
@@ -111,7 +112,8 @@
 
   void testNormalRange(RemQuoFunc func) {
     constexpr UIntType COUNT = 1'001;
-    constexpr UIntType STEP = (FPBits::MAX_NORMAL - FPBits::MIN_NORMAL) / COUNT;
+    constexpr UIntType STEP =
+        (UIntType(FPBits::MAX_NORMAL) - UIntType(FPBits::MIN_NORMAL)) / COUNT;
     for (UIntType v = FPBits::MIN_NORMAL, w = FPBits::MAX_NORMAL;
          v <= FPBits::MAX_NORMAL && w >= FPBits::MIN_NORMAL;
          v += STEP, w -= STEP) {
diff --git a/libc/test/src/math/RoundToIntegerTest.h b/libc/test/src/math/RoundToIntegerTest.h
--- a/libc/test/src/math/RoundToIntegerTest.h
+++ b/libc/test/src/math/RoundToIntegerTest.h
@@ -216,7 +216,8 @@
   void testSubnormalRange(RoundToIntegerFunc func) {
     constexpr UIntType COUNT = 1'000'001;
     constexpr UIntType STEP =
-        (FPBits::MAX_SUBNORMAL - FPBits::MIN_SUBNORMAL) / COUNT;
+        (UIntType(FPBits::MAX_SUBNORMAL) - UIntType(FPBits::MIN_SUBNORMAL)) /
+        COUNT;
     for (UIntType i = FPBits::MIN_SUBNORMAL; i <= FPBits::MAX_SUBNORMAL;
          i += STEP) {
       F x = F(FPBits(i));
@@ -259,7 +260,8 @@
       return;
 
     constexpr UIntType COUNT = 1'000'001;
-    constexpr UIntType STEP = (FPBits::MAX_NORMAL - FPBits::MIN_NORMAL) / COUNT;
+    constexpr UIntType STEP =
+        (UIntType(FPBits::MAX_NORMAL) - UIntType(FPBits::MIN_NORMAL)) / COUNT;
     for (UIntType i = FPBits::MIN_NORMAL; i <= FPBits::MAX_NORMAL; i += STEP) {
       F x = F(FPBits(i));
       // In normal range on x86 platforms, the long double implicit 1 bit can be