diff --git a/plist-cil.test/NSNumberTests.cs b/plist-cil.test/NSNumberTests.cs
index c4cbc52..9075a3f 100644
--- a/plist-cil.test/NSNumberTests.cs
+++ b/plist-cil.test/NSNumberTests.cs
@@ -72,6 +72,24 @@ namespace plistcil.test
             Assert.Equal(doubleValue, number.ToDouble(), 5);
         }
 
+        [Fact]
+        public void SpanConstructorInvalidValuesTest()
+        {
+            Assert.Throws<ArgumentNullException>(() => new NSNumber((Span<byte>)null, NSNumber.INTEGER));
+            Assert.Throws<ArgumentNullException>(() => new NSNumber((Span<byte>)null, NSNumber.REAL));
+            Assert.Throws<ArgumentOutOfRangeException>(() => new NSNumber((Span<byte>)Array.Empty<byte>(), NSNumber.INTEGER));
+            Assert.Throws<ArgumentException>(() => new NSNumber((Span<byte>)Array.Empty<byte>(), NSNumber.REAL));
+            Assert.Throws<ArgumentException>(() => new NSNumber((Span<byte>)Array.Empty<byte>(), 9));
+        }
+
+        [Fact]
+        public void StringAndTypeConstructorInvalidValuesTest()
+        {
+            Assert.Throws<ArgumentNullException>(() => new NSNumber((string)null, NSNumber.INTEGER));
+            Assert.Throws<ArgumentNullException>(() => new NSNumber((string)null, NSNumber.REAL));
+            Assert.Throws<ArgumentException>(() => new NSNumber("0", 9));
+        }
+
         [Fact]
         public static void NSNumberConstructorTest()
         {
@@ -138,7 +156,149 @@ namespace plistcil.test
             Assert.True(number.isReal());
             Assert.Equal(7200d, number.ToDouble());
         }
-        #endif
+#endif
+
+        public static IEnumerable<object[]> StringConstructorTestData()
+        {
+            return new List<object[]>
+            {
+                // Long values, formatted as hexadecimal values
+                new object[] { "0x00", false, 0, 0.0 },
+                new object[] { "0x1000", true, 0x1000, 1.0 * 0x1000 },
+                new object[] { "0x00001000", true, 0x1000, 1.0 * 0x1000 },
+                new object[] { "0x0000000000001000", true, 0x1000, 1.0 * 0x1000 },
+
+                // Long values, formatted as decimal values
+                new object[] { "0", false, 0, 0.0 },
+                new object[] { "10", true, 10, 10.0 },
+                
+                // Decimal values
+                new object[] { "0.0", false, 0, 0.0 },
+                new object[] { "0.10", false, 0, 0.1 },
+                new object[] { "3.14", true, 3, 3.14 },
+
+                // Boolean values
+                new object[] { "yes", true, 1, 1},
+                new object[] { "true", true, 1, 1},
+                new object[] { "Yes", true, 1, 1},
+                new object[] { "True", true, 1, 1},
+                new object[] { "YES", true, 1, 1},
+                new object[] { "TRUE", true, 1, 1},
+
+                new object[] { "no", false, 0, 0},
+                new object[] { "false", false, 0, 0},
+                new object[] { "No", false, 0, 0},
+                new object[] { "False", false, 0, 0},
+                new object[] { "NO", false, 0, 0},
+                new object[] { "FALSE", false, 0, 0},
+            };
+        }
+
+        [Theory]
+        [MemberData(nameof(StringConstructorTestData))]
+        public void StringConstructorTest(string value, bool boolValue, long longValue, double doubleValue)
+        {
+            NSNumber number = new NSNumber(value);
+            Assert.Equal(boolValue, number.ToBool());
+            Assert.Equal(longValue, number.ToLong());
+            Assert.Equal(doubleValue, number.ToDouble(), 5);
+        }
+
+        [Fact]
+        public void StringConstructorInvalidValuesTest()
+        {
+            Assert.Throws<ArgumentException>(() => new NSNumber(null));
+            Assert.Throws<ArgumentException>(() => new NSNumber("plist"));
+        }
+
+        public static IEnumerable<object[]> Int32ConstructorTestData()
+        {
+            return new List<object[]>
+            {
+                // Long values, formatted as hexadecimal values
+                new object[] { 0, false, 0, 0.0 },
+                new object[] { 1, true, 1, 1.0 },
+                new object[] { -1, true, -1, -1.0 },
+                new object[] { int.MaxValue, true, int.MaxValue, int.MaxValue },
+                new object[] { int.MinValue, true, int.MinValue, int.MinValue },
+            };
+        }
+
+        [Theory]
+        [MemberData(nameof(Int32ConstructorTestData))]
+        public void Int32ConstructorTest(int value, bool boolValue, long longValue, double doubleValue)
+        {
+            NSNumber number = new NSNumber(value);
+            Assert.Equal(boolValue, number.ToBool());
+            Assert.Equal(longValue, number.ToLong());
+            Assert.Equal(doubleValue, number.ToDouble(), 5);
+        }
+
+        public static IEnumerable<object[]> Int64ConstructorTestData()
+        {
+            return new List<object[]>
+            {
+                // Long values, formatted as hexadecimal values
+                new object[] { 0, false, 0, 0.0 },
+                new object[] { 1, true, 1, 1.0 },
+                new object[] { -1, true, -1, -1.0 },
+                new object[] { long.MaxValue, true, long.MaxValue, long.MaxValue },
+                new object[] { long.MinValue, true, long.MinValue, long.MinValue },
+            };
+        }
+
+        [Theory]
+        [MemberData(nameof(Int64ConstructorTestData))]
+        public void Int64ConstructorTest(long value, bool boolValue, long longValue, double doubleValue)
+        {
+            NSNumber number = new NSNumber(value);
+            Assert.Equal(boolValue, number.ToBool());
+            Assert.Equal(longValue, number.ToLong());
+            Assert.Equal(doubleValue, number.ToDouble(), 5);
+        }
+
+        public static IEnumerable<object[]> DoubleConstructorTestData()
+        {
+            return new List<object[]>
+            {
+                // Long values, formatted as hexadecimal values
+                new object[] { 0.0, false, 0, 0.0 },
+                new object[] { 1.0, true, 1, 1.0 },
+                new object[] { -1.0, true, -1, -1.0 },
+                new object[] { double.Epsilon, false, 0, double.Epsilon },
+                new object[] { double.MaxValue, true, long.MinValue /* Overflow! */, double.MaxValue },
+                new object[] { double.MinValue, true, long.MinValue, double.MinValue },
+            };
+        }
+
+        [Theory]
+        [MemberData(nameof(DoubleConstructorTestData))]
+        public void DoubleConstructorTest(double value, bool boolValue, long longValue, double doubleValue)
+        {
+            NSNumber number = new NSNumber(value);
+            Assert.Equal(boolValue, number.ToBool());
+            Assert.Equal(longValue, number.ToLong());
+            Assert.Equal(doubleValue, number.ToDouble(), 5);
+        }
+        public static IEnumerable<object[]> BoolConstructorTestData()
+        {
+            return new List<object[]>
+            {
+                // Long values, formatted as hexadecimal values
+                new object[] { false, false, 0, 0.0 },
+                new object[] { true, true, 1, 1.0 },
+            };
+        }
+
+        [Theory]
+        [MemberData(nameof(BoolConstructorTestData))]
+        public void BoolConstructorTest(bool value, bool boolValue, long longValue, double doubleValue)
+        {
+            NSNumber number = new NSNumber(value);
+            Assert.Equal(boolValue, number.ToBool());
+            Assert.Equal(longValue, number.ToLong());
+            Assert.Equal(doubleValue, number.ToDouble(), 5);
+        }
 
         [Fact]
         public void EqualTest()
diff --git a/plist-cil/BinaryPropertyListParser.cs b/plist-cil/BinaryPropertyListParser.cs
index 88a29d4..d53d536 100644
--- a/plist-cil/BinaryPropertyListParser.cs
+++ b/plist-cil/BinaryPropertyListParser.cs
@@ -515,6 +515,16 @@ namespace Claunia.PropertyList
         /// <param name="bytes">The bytes representing the long integer.</param>
         public static long ParseLong(ReadOnlySpan<byte> bytes)
         {
+            if(bytes == null)
+            {
+                throw new ArgumentNullException(nameof(bytes));
+            }
+
+            if(bytes.Length == 0)
+            {
+                throw new ArgumentOutOfRangeException(nameof(bytes));
+            }
+
             // https://opensource.apple.com/source/CF/CF-1153.18/CFBinaryPList.c,
             // __CFBinaryPlistCreateObjectFiltered, case kCFBinaryPlistMarkerInt:
             // 
@@ -564,6 +574,11 @@ namespace Claunia.PropertyList
         /// <param name="bytes">The bytes representing the double.</param>
         public static double ParseDouble(ReadOnlySpan<byte> bytes)
         {
+            if(bytes == null)
+            {
+                throw new ArgumentNullException(nameof(bytes));
+            }
+
             if(bytes.Length == 8) return BitConverter.Int64BitsToDouble(ParseLong(bytes));
             if(bytes.Length == 4) return BitConverter.ToSingle(BitConverter.GetBytes(ParseLong(bytes)), 0);
 
diff --git a/plist-cil/NSNumber.cs b/plist-cil/NSNumber.cs
index ed91a94..272d3d1 100644
--- a/plist-cil/NSNumber.cs
+++ b/plist-cil/NSNumber.cs
@@ -83,7 +83,7 @@ namespace Claunia.PropertyList
                     longValue   = (long)Math.Round(doubleValue);
                     break;
 
-                default: throw new ArgumentException("Type argument is not valid.");
+                default: throw new ArgumentException("Type argument is not valid.", nameof(type));
             }
 
             this.type = type;
@@ -124,13 +124,12 @@ namespace Claunia.PropertyList
             long   l;
             double d;
 
-            if(text.StartsWith("0x") && long.TryParse("", NumberStyles.HexNumber, CultureInfo.InvariantCulture, out l))
+            if(text.StartsWith("0x") && long.TryParse(text.Substring(2), NumberStyles.AllowHexSpecifier, CultureInfo.InvariantCulture, out l))
             {
                 doubleValue = longValue = l;
                 type        = INTEGER;
             }
-
-            if(long.TryParse(text, NumberStyles.Number, CultureInfo.InvariantCulture, out l))
+            else if(long.TryParse(text, NumberStyles.Number, CultureInfo.InvariantCulture, out l))
             {
                 doubleValue = longValue = l;
                 type        = INTEGER;
@@ -151,6 +150,7 @@ namespace Claunia.PropertyList
                 if(isTrue || isFalse)
                 {
                     type        = BOOLEAN;
+                    boolValue   = isTrue;
                     doubleValue = longValue = boolValue ? 1 : 0;
                 }
                 else