diff --git a/libc/src/__support/FPUtil/Hypot.h b/libc/src/__support/FPUtil/Hypot.h
--- a/libc/src/__support/FPUtil/Hypot.h
+++ b/libc/src/__support/FPUtil/Hypot.h
@@ -150,7 +150,7 @@
     return abs(y);
   }
 
-  if (x >= y) {
+  if (abs(x) >= abs(y)) {
     a_exp = x_bits.getUnbiasedExponent();
     a_mant = x_bits.getMantissa();
     b_exp = y_bits.getUnbiasedExponent();
@@ -178,10 +178,13 @@
     y_mant_width = MantissaWidth<T>::value + 1;
   } else {
     leading_one = internal::findLeadingOne(a_mant, y_mant_width);
+    a_exp = 1;
   }
 
   if (b_exp != 0) {
     b_mant |= one;
+  } else {
+    b_exp = 1;
   }
 
   a_mant_sq = static_cast<DUIntType>(a_mant) * a_mant;
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
@@ -47,28 +47,47 @@
 
   void testSubnormalRange(Func func) {
     constexpr UIntType count = 1000001;
-    constexpr UIntType step =
-        (FPBits::maxSubnormal - FPBits::minSubnormal) / count;
-    for (UIntType v = FPBits::minSubnormal, w = FPBits::maxSubnormal;
-         v <= FPBits::maxSubnormal && w >= FPBits::minSubnormal;
-         v += step, w -= step) {
-      T x = T(FPBits(v)), y = T(FPBits(w));
-      T result = func(x, y);
-      mpfr::BinaryInput<T> input{x, y};
-      ASSERT_MPFR_MATCH(mpfr::Operation::Hypot, input, result, 0.5);
+    for (unsigned scale = 0; scale < 4; ++scale) {
+      UIntType maxValue = FPBits::maxSubnormal << scale;
+      UIntType step = (maxValue - FPBits::minSubnormal) / count;
+      for (int signs = 0; signs < 4; ++signs) {
+        for (UIntType v = FPBits::minSubnormal, w = maxValue;
+             v <= maxValue && w >= FPBits::minSubnormal; v += step, w -= step) {
+          T x = T(FPBits(v)), y = T(FPBits(w));
+          if (signs % 2 == 1) {
+            x = -x;
+          }
+          if (signs >= 2) {
+            y = -y;
+          }
+
+          T result = func(x, y);
+          mpfr::BinaryInput<T> input{x, y};
+          ASSERT_MPFR_MATCH(mpfr::Operation::Hypot, input, result, 0.5);
+        }
+      }
     }
   }
 
   void testNormalRange(Func func) {
     constexpr UIntType count = 1000001;
     constexpr UIntType step = (FPBits::maxNormal - FPBits::minNormal) / count;
-    for (UIntType v = FPBits::minNormal, w = FPBits::maxNormal;
-         v <= FPBits::maxNormal && w >= FPBits::minNormal;
-         v += step, w -= step) {
-      T x = T(FPBits(v)), y = T(FPBits(w));
-      T result = func(x, y);
-      mpfr::BinaryInput<T> input{x, y};
-      ASSERT_MPFR_MATCH(mpfr::Operation::Hypot, input, result, 0.5);
+    for (int signs = 0; signs < 4; ++signs) {
+      for (UIntType v = FPBits::minNormal, w = FPBits::maxNormal;
+           v <= FPBits::maxNormal && w >= FPBits::minNormal;
+           v += step, w -= step) {
+        T x = T(FPBits(v)), y = T(FPBits(w));
+        if (signs % 2 == 1) {
+          x = -x;
+        }
+        if (signs >= 2) {
+          y = -y;
+        }
+
+        T result = func(x, y);
+        mpfr::BinaryInput<T> input{x, y};
+        ASSERT_MPFR_MATCH(mpfr::Operation::Hypot, input, result, 0.5);
+      }
     }
   }
 };
diff --git a/libc/utils/MPFRWrapper/MPFRUtils.cpp b/libc/utils/MPFRWrapper/MPFRUtils.cpp
--- a/libc/utils/MPFRWrapper/MPFRUtils.cpp
+++ b/libc/utils/MPFRWrapper/MPFRUtils.cpp
@@ -312,11 +312,18 @@
 
     int thisExponent = fputil::FPBits<T>(thisAsT).getExponent();
     int inputExponent = fputil::FPBits<T>(input).getExponent();
+    if (fputil::FPBits<T>(thisAsT).getUnbiasedExponent() == 0)
+      ++thisExponent;
+    if (fputil::FPBits<T>(input).getUnbiasedExponent() == 0)
+      ++inputExponent;
+
     if (thisAsT * input < 0 || thisExponent == inputExponent) {
       MPFRNumber inputMPFR(input);
       mpfr_sub(inputMPFR.value, value, inputMPFR.value, MPFR_RNDN);
       mpfr_abs(inputMPFR.value, inputMPFR.value, MPFR_RNDN);
-      mpfr_mul_2si(inputMPFR.value, inputMPFR.value, -thisExponent, MPFR_RNDN);
+      mpfr_mul_2si(inputMPFR.value, inputMPFR.value,
+                   -thisExponent + int(fputil::MantissaWidth<T>::value),
+                   MPFR_RNDN);
       return inputMPFR.as<double>();
     }
 
@@ -329,6 +336,10 @@
     T max = thisAsT > input ? thisAsT : input;
     int minExponent = fputil::FPBits<T>(min).getExponent();
     int maxExponent = fputil::FPBits<T>(max).getExponent();
+    if (fputil::FPBits<T>(min).getUnbiasedExponent() == 0)
+      ++minExponent;
+    if (fputil::FPBits<T>(max).getUnbiasedExponent() == 0)
+      ++maxExponent;
 
     MPFRNumber minMPFR(min);
     MPFRNumber maxMPFR(max);
@@ -337,10 +348,14 @@
     mpfr_mul_2si(pivot.value, pivot.value, maxExponent, MPFR_RNDN);
 
     mpfr_sub(minMPFR.value, pivot.value, minMPFR.value, MPFR_RNDN);
-    mpfr_mul_2si(minMPFR.value, minMPFR.value, -minExponent, MPFR_RNDN);
+    mpfr_mul_2si(minMPFR.value, minMPFR.value,
+                 -minExponent + int(fputil::MantissaWidth<T>::value),
+                 MPFR_RNDN);
 
     mpfr_sub(maxMPFR.value, maxMPFR.value, pivot.value, MPFR_RNDN);
-    mpfr_mul_2si(maxMPFR.value, maxMPFR.value, -maxExponent, MPFR_RNDN);
+    mpfr_mul_2si(maxMPFR.value, maxMPFR.value,
+                 -maxExponent + int(fputil::MantissaWidth<T>::value),
+                 MPFR_RNDN);
 
     mpfr_add(minMPFR.value, minMPFR.value, maxMPFR.value, MPFR_RNDN);
     return minMPFR.as<double>();