diff --git a/Unosquare.RaspberryIO.Abstractions/Definitions.cs b/Unosquare.RaspberryIO.Abstractions/Definitions.cs
index ba537e8..000cb00 100644
--- a/Unosquare.RaspberryIO.Abstractions/Definitions.cs
+++ b/Unosquare.RaspberryIO.Abstractions/Definitions.cs
@@ -7,7 +7,11 @@ namespace Unosquare.RaspberryIO.Abstractions {
   public static class Definitions {
     private static readonly Int32[] GpioToPhysR1 = { 3, 5, -1, -1, 7, -1, -1, 26, 24, 21, 19, 23, -1, -1, 8, 10, -1, 11, 12, -1, -1, 13, 15, 16, 18, 22, -1, -1, -1, -1, -1, -1 };
 
-    private static readonly Int32[] GpioToPhysR2 = { 27, 28, 3, 5, 7, 29, 31, 26, 24, 21, 19, 23, 32, 33, 8, 10, 36, 11, 12, 35, 38, 40, 15, 16, 18, 22, 37, 13, /*P1*/ 3, 4, 5, 6 /*P5*/ };
+    private static readonly Int32[] GpioToPhysR2 =
+    {
+      27, 28, 3, 5, 7, 29, 31, 26, 24, 21, 19, 23, 32, 33, 8, 10, 36, 11, 12, 35, 38, 40, 15, 16, 18, 22, 37, 13, // P1
+      3, 4, 5, 6, // P5
+    };
 
     /// <summary>
     /// BCMs to physical pin number.
diff --git a/Unosquare.RaspberryIO.Abstractions/IGpioController.cs b/Unosquare.RaspberryIO.Abstractions/IGpioController.cs
index 95e8fb0..f78c737 100644
--- a/Unosquare.RaspberryIO.Abstractions/IGpioController.cs
+++ b/Unosquare.RaspberryIO.Abstractions/IGpioController.cs
@@ -6,45 +6,45 @@ namespace Unosquare.RaspberryIO.Abstractions {
   /// Interface for Raspberry Pi GPIO controller.
   /// </summary>
   /// <seealso cref="System.Collections.Generic.IReadOnlyCollection{IGpioPin}" />
-  public interface IGpioController : IReadOnlyCollection<IGpioPin> {
-    /// <summary>
-    /// Gets the <see cref="IGpioPin"/> with the specified BCM pin.
-    /// </summary>
-    /// <value>
-    /// The <see cref="IGpioPin"/>.
-    /// </value>
-    /// <param name="bcmPinNumber">The BCM pin number.</param>
-    /// <returns>A reference to the GPIO pin.</returns>
-    IGpioPin this[Int32 bcmPinNumber] { get; }
-
-    /// <summary>
-    /// Gets the <see cref="IGpioPin"/> with the specified BCM pin.
-    /// </summary>
-    /// <value>
-    /// The <see cref="IGpioPin"/>.
-    /// </value>
-    /// <param name="bcmPin">The BCM pin.</param>
-    /// <returns>A reference to the GPIO pin.</returns>
-    IGpioPin this[BcmPin bcmPin] { get; }
-
-    /// <summary>
-    /// Gets the <see cref="IGpioPin"/> with the specified pin number.
-    /// </summary>
-    /// <value>
-    /// The <see cref="IGpioPin"/>.
-    /// </value>
-    /// <param name="pinNumber">The pin number in header P1.</param>
-    /// <returns>A reference to the GPIO pin.</returns>
-    IGpioPin this[P1 pinNumber] { get; }
-
-    /// <summary>
-    /// Gets the <see cref="IGpioPin"/> with the specified pin number.
-    /// </summary>
-    /// <value>
-    /// The <see cref="IGpioPin"/>.
-    /// </value>
-    /// <param name="pinNumber">The pin number in header P5.</param>
-    /// <returns>A reference to the GPIO pin.</returns>
-    IGpioPin this[P5 pinNumber] { get; }
-  }
+  public interface IGpioController : IReadOnlyCollection<IGpioPin> {
+        /// <summary>
+        /// Gets the <see cref="IGpioPin"/> with the specified BCM pin.
+        /// </summary>
+        /// <value>
+        /// The <see cref="IGpioPin"/>.
+        /// </value>
+        /// <param name="bcmPinNumber">The BCM pin number.</param>
+        /// <returns>A reference to the GPIO pin.</returns>
+        IGpioPin this[Int32 bcmPinNumber] { get; }
+
+        /// <summary>
+        /// Gets the <see cref="IGpioPin"/> with the specified BCM pin.
+        /// </summary>
+        /// <value>
+        /// The <see cref="IGpioPin"/>.
+        /// </value>
+        /// <param name="bcmPin">The BCM pin.</param>
+        /// <returns>A reference to the GPIO pin.</returns>
+        IGpioPin this[BcmPin bcmPin] { get; }
+
+        /// <summary>
+        /// Gets the <see cref="IGpioPin"/> with the specified pin number.
+        /// </summary>
+        /// <value>
+        /// The <see cref="IGpioPin"/>.
+        /// </value>
+        /// <param name="pinNumber">The pin number in header P1.</param>
+        /// <returns>A reference to the GPIO pin.</returns>
+        IGpioPin this[P1 pinNumber] { get; }
+
+        /// <summary>
+        /// Gets the <see cref="IGpioPin"/> with the specified pin number.
+        /// </summary>
+        /// <value>
+        /// The <see cref="IGpioPin"/>.
+        /// </value>
+        /// <param name="pinNumber">The pin number in header P5.</param>
+        /// <returns>A reference to the GPIO pin.</returns>
+        IGpioPin this[P5 pinNumber] { get; }
+    }
 }
diff --git a/Unosquare.RaspberryIO.Abstractions/II2CBus.cs b/Unosquare.RaspberryIO.Abstractions/II2CBus.cs
index 4de8ec8..9de57c5 100644
--- a/Unosquare.RaspberryIO.Abstractions/II2CBus.cs
+++ b/Unosquare.RaspberryIO.Abstractions/II2CBus.cs
@@ -1,6 +1,6 @@
 using System;
-using System.Collections.ObjectModel;
-
+using System.Collections.ObjectModel;
+
 namespace Unosquare.RaspberryIO.Abstractions {
   /// <summary>
   /// Interfaces the I2c bus on the Raspberry Pi.
diff --git a/Unosquare.RaspberryIO.Abstractions/Native/HardwareException.cs b/Unosquare.RaspberryIO.Abstractions/Native/HardwareException.cs
index ef80274..cb89cfe 100644
--- a/Unosquare.RaspberryIO.Abstractions/Native/HardwareException.cs
+++ b/Unosquare.RaspberryIO.Abstractions/Native/HardwareException.cs
@@ -1,3 +1,5 @@
+#nullable enable
+
 using System;
 using System.Runtime.InteropServices;
 
diff --git a/Unosquare.RaspberryIO.Abstractions/Native/Standard.cs b/Unosquare.RaspberryIO.Abstractions/Native/Standard.cs
index 0fc7516..fa2c349 100644
--- a/Unosquare.RaspberryIO.Abstractions/Native/Standard.cs
+++ b/Unosquare.RaspberryIO.Abstractions/Native/Standard.cs
@@ -16,7 +16,7 @@ namespace Unosquare.RaspberryIO.Abstractions.Native {
     /// </summary>
     /// <param name="error">The error.</param>
     /// <returns>The error string.</returns>
-    public static String? Strerror(Int32 error) {
+    public static String Strerror(Int32 error) {
       if(Type.GetType("Mono.Runtime") == null) {
         return Marshal.PtrToStringAnsi(StrError(error));
       }
diff --git a/Unosquare.RaspberryIO.Abstractions/Unosquare.RaspberryIO.Abstractions.csproj b/Unosquare.RaspberryIO.Abstractions/Unosquare.RaspberryIO.Abstractions.csproj
index fa41119..fd82b8c 100644
--- a/Unosquare.RaspberryIO.Abstractions/Unosquare.RaspberryIO.Abstractions.csproj
+++ b/Unosquare.RaspberryIO.Abstractions/Unosquare.RaspberryIO.Abstractions.csproj
@@ -16,7 +16,6 @@ This library enables developers to use the various Raspberry Pi's hardware modul
     <PackageLicenseUrl>https://raw.githubusercontent.com/unosquare/raspberryio/master/LICENSE</PackageLicenseUrl>
     <PackageTags>Raspberry Pi GPIO Camera SPI I2C Embedded IoT Mono C# .NET</PackageTags>
     <LangVersion>8.0</LangVersion>
-	<Nullable>enable</Nullable>
   </PropertyGroup>
 
 </Project>