diff --git a/Foundation/Decimal.swift b/Foundation/Decimal.swift
index 175dfcc674..c650f67cc2 100644
--- a/Foundation/Decimal.swift
+++ b/Foundation/Decimal.swift
@@ -101,7 +101,7 @@ public struct Decimal {
 
 extension Decimal {
     public static let leastFiniteMagnitude = Decimal(
-        _exponent: 127,
+        _exponent: Int32(Int8.max),
         _length: 8,
         _isNegative: 1,
         _isCompact: 1,
@@ -109,7 +109,7 @@ extension Decimal {
         _mantissa: (0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff)
     )
     public static let greatestFiniteMagnitude = Decimal(
-        _exponent: 127,
+        _exponent: Int32(Int8.max),
         _length: 8,
         _isNegative: 0,
         _isCompact: 1,
@@ -117,7 +117,7 @@ extension Decimal {
         _mantissa: (0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff)
     )
     public static let leastNormalMagnitude = Decimal(
-        _exponent: -127,
+        _exponent: Int32(Int8.min),
         _length: 1,
         _isNegative: 0,
         _isCompact: 1,
@@ -125,7 +125,7 @@ extension Decimal {
         _mantissa: (0x0001, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000)
     )
     public static let leastNonzeroMagnitude = Decimal(
-        _exponent: -127,
+        _exponent: Int32(Int8.min),
         _length: 1,
         _isNegative: 0,
         _isCompact: 1,
diff --git a/TestFoundation/TestDecimal.swift b/TestFoundation/TestDecimal.swift
index 38acd3d37a..66d1401479 100644
--- a/TestFoundation/TestDecimal.swift
+++ b/TestFoundation/TestDecimal.swift
@@ -34,6 +34,8 @@ class TestDecimal: XCTestCase {
             ("test_doubleValue", test_doubleValue),
             ("test_NSDecimalNumberValues", test_NSDecimalNumberValues),
             ("test_bridging", test_bridging),
+            ("test_LeastMagnitude", test_LeastMagnitude),
+            ("test_GreatestMagnitude", test_GreatestMagnitude),
         ]
     }
 
@@ -167,9 +169,9 @@ class TestDecimal: XCTestCase {
         XCTAssertEqual(smallest, Decimal.leastFiniteMagnitude)
         let biggest = Decimal(_exponent: 127, _length: 8, _isNegative: 0, _isCompact: 1, _reserved: 0, _mantissa: (UInt16.max, UInt16.max, UInt16.max, UInt16.max, UInt16.max, UInt16.max, UInt16.max, UInt16.max))
         XCTAssertEqual(biggest, Decimal.greatestFiniteMagnitude)
-        let leastNormal = Decimal(_exponent: -127, _length: 1, _isNegative: 0, _isCompact: 1, _reserved: 0, _mantissa: (1, 0, 0, 0, 0, 0, 0, 0))
+        let leastNormal = Decimal(_exponent: -128, _length: 1, _isNegative: 0, _isCompact: 1, _reserved: 0, _mantissa: (1, 0, 0, 0, 0, 0, 0, 0))
         XCTAssertEqual(leastNormal, Decimal.leastNormalMagnitude)
-        let leastNonzero = Decimal(_exponent: -127, _length: 1, _isNegative: 0, _isCompact: 1, _reserved: 0, _mantissa: (1, 0, 0, 0, 0, 0, 0, 0))
+        let leastNonzero = Decimal(_exponent: -128, _length: 1, _isNegative: 0, _isCompact: 1, _reserved: 0, _mantissa: (1, 0, 0, 0, 0, 0, 0, 0))
         XCTAssertEqual(leastNonzero, Decimal.leastNonzeroMagnitude)
         let pi = Decimal(_exponent: -38, _length: 8, _isNegative: 0, _isCompact: 1, _reserved: 0, _mantissa: (0x6623, 0x7d57, 0x16e7, 0xad0d, 0xaf52, 0x4641, 0xdfa7, 0xec58))
         XCTAssertEqual(pi, Decimal.pi)
@@ -761,6 +763,23 @@ class TestDecimal: XCTestCase {
         XCTAssertEqual(1, negativeSix.raising(toPower: 0))
     }
 
+    func test_LeastMagnitude() {
+        var result = Decimal()
+
+        var leastNormal = Decimal.leastNormalMagnitude
+        XCTAssertEqual(.underflow, NSDecimalMultiplyByPowerOf10(&result, &leastNormal, -1, .plain))
+
+        var leastNonzero = Decimal.leastNonzeroMagnitude
+        XCTAssertEqual(.underflow, NSDecimalMultiplyByPowerOf10(&result, &leastNonzero, -1, .plain))
+    }
+
+    func test_GreatestMagnitude() {
+        var result = Decimal()
+
+        var greatest = Decimal.greatestFiniteMagnitude
+        XCTAssertEqual(.overflow, NSDecimalMultiplyByPowerOf10(&result, &greatest, 1, .plain))
+    }
+
     func test_doubleValue() {
         XCTAssertEqual(NSDecimalNumber(decimal:Decimal(0)).doubleValue, 0)
         XCTAssertEqual(NSDecimalNumber(decimal:Decimal(1)).doubleValue, 1)
diff --git a/TestFoundation/TestJSONSerialization.swift b/TestFoundation/TestJSONSerialization.swift
index af3cf5d0b3..b03d5a3fec 100644
--- a/TestFoundation/TestJSONSerialization.swift
+++ b/TestFoundation/TestJSONSerialization.swift
@@ -1301,8 +1301,8 @@ extension TestJSONSerialization {
     func test_serialize_Decimal() {
         XCTAssertEqual(try trySerialize([-Decimal.leastFiniteMagnitude]), "[3402823669209384634633746074317682114550000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000]")
         XCTAssertEqual(try trySerialize([Decimal.leastFiniteMagnitude]), "[-3402823669209384634633746074317682114550000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000]")
-        XCTAssertEqual(try trySerialize([-Decimal.leastNonzeroMagnitude]), "[-0.0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001]")
-        XCTAssertEqual(try trySerialize([Decimal.leastNonzeroMagnitude]), "[0.0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001]")
+        XCTAssertEqual(try trySerialize([-Decimal.leastNonzeroMagnitude]), "[-0.00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001]")
+        XCTAssertEqual(try trySerialize([Decimal.leastNonzeroMagnitude]), "[0.00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001]")
         XCTAssertEqual(try trySerialize([-Decimal.greatestFiniteMagnitude]), "[-3402823669209384634633746074317682114550000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000]")
         XCTAssertEqual(try trySerialize([Decimal.greatestFiniteMagnitude]), "[3402823669209384634633746074317682114550000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000]")
         XCTAssertEqual(try trySerialize([Decimal(Int8.min), Decimal(Int8(0)), Decimal(Int8.max)]), "[-128,0,127]")