diff --git a/src/bignum/bignum.cc b/src/bignum/bignum.cc
index 3fce460..cadc170 100644
--- a/src/bignum/bignum.cc
+++ b/src/bignum/bignum.cc
@@ -363,11 +363,7 @@ bool BigNum::less_than(BigNum const& rhs) const {
         return sign_ < rhs.sign_;
     }
 
-    if (is_positive()) {
-        return do_less_than(digits_, rhs.digits_);
-    } else {
-        return do_less_than(rhs.digits_, digits_);
-    }
+    return do_less_than(digits_, rhs.digits_);
 }
 
 void BigNum::canonicalize() {
@@ -385,15 +381,15 @@ bool BigNum::is_canonicalized() const {
         return sign_ == 0;
     }
 
-    // `back` is valid since there is at least one element
-    auto const has_leading_zero = digits_.back() == 0;
-    if (has_leading_zero) {
+    auto const leading_zeros = std::find_if(digits_.rbegin(), digits_.rend(),
+                                            [](auto v) { return v != 0; });
+    if (leading_zeros != digits_.rbegin()) {
         return false;
     }
 
-    auto const has_overflow = std::any_of(digits_.begin(), digits_.end(),
-                                          [](auto v) { return v >= BASE; });
-    if (has_overflow) {
+    auto const overflow = std::find_if(digits_.begin(), digits_.end(),
+                                       [](auto v) { return v >= BASE; });
+    if (overflow != digits_.end()) {
         return false;
     }
 
diff --git a/tests/unit/bignum.cc b/tests/unit/bignum.cc
index 1126a17..b7306f4 100644
--- a/tests/unit/bignum.cc
+++ b/tests/unit/bignum.cc
@@ -68,34 +68,6 @@ TEST(BigNum, comparisons_digits) {
     EXPECT_GT(ten, nine);
 }
 
-TEST(BigNum, comparisons_negative) {
-    auto const zero = BigNum(0);
-    auto const minus_one = BigNum(-1);
-    auto const minus_two = BigNum(-2);
-
-    EXPECT_LT(minus_one, zero);
-    EXPECT_LE(minus_one, zero);
-    EXPECT_LT(minus_two, minus_one);
-    EXPECT_LE(minus_two, minus_one);
-    EXPECT_LE(minus_one, minus_one);
-    EXPECT_GE(minus_two, minus_two);
-
-    EXPECT_GT(zero, minus_one);
-    EXPECT_GE(zero, minus_one);
-    EXPECT_GT(minus_one, minus_two);
-    EXPECT_GE(minus_one, minus_two);
-    EXPECT_GE(minus_one, minus_one);
-    EXPECT_GE(minus_two, minus_two);
-}
-
-TEST(BigNum, comparisons_digits_negative) {
-    auto const minus_nine = BigNum(-9);
-    auto const minus_ten = BigNum(-10);
-
-    EXPECT_LT(minus_ten, minus_nine);
-    EXPECT_GT(minus_nine, minus_ten);
-}
-
 TEST(BigNum, unary) {
     auto const zero = BigNum(0);
     auto const one = BigNum(1);