diff --git a/src/CarbonAware.DataSources/CarbonAware.DataSources.ElectricityMaps/mock/ElectricityMapDataSourceMocker.cs b/src/CarbonAware.DataSources/CarbonAware.DataSources.ElectricityMaps/mock/ElectricityMapDataSourceMocker.cs
index 4a2875133..2009926b0 100644
--- a/src/CarbonAware.DataSources/CarbonAware.DataSources.ElectricityMaps/mock/ElectricityMapDataSourceMocker.cs
+++ b/src/CarbonAware.DataSources/CarbonAware.DataSources.ElectricityMaps/mock/ElectricityMapDataSourceMocker.cs
@@ -12,7 +12,7 @@ namespace CarbonAware.DataSources.ElectricityMaps.Mocks;
 
 public class ElectricityMapsDataSourceMocker : IDataSourceMocker
 {
-    private WireMockServer _server;
+    private readonly WireMockServer _server;
     private const string ZONE_NAME = "eastus";
     private const string ZONE_KEY = "US-NE-ISNE";
     private static readonly JsonSerializerOptions _options = new JsonSerializerOptions(JsonSerializerDefaults.Web);
diff --git a/src/CarbonAware.DataSources/CarbonAware.DataSources.ElectricityMaps/src/ElectricityMapsDataSource.cs b/src/CarbonAware.DataSources/CarbonAware.DataSources.ElectricityMaps/src/ElectricityMapsDataSource.cs
index 81ca4b5eb..c45fb52dc 100644
--- a/src/CarbonAware.DataSources/CarbonAware.DataSources.ElectricityMaps/src/ElectricityMapsDataSource.cs
+++ b/src/CarbonAware.DataSources/CarbonAware.DataSources.ElectricityMaps/src/ElectricityMapsDataSource.cs
@@ -69,7 +69,7 @@ private static EmissionsForecast ToEmissionsForecast(Location location, Forecast
         emissionsForecast.RequestedAt = requestedAt;
         emissionsForecast.ForecastData = emissionsForecast.ForecastData.Select(d =>
         {
-            d.Location = location.Name;
+            d.Location = location.Name ?? string.Empty;
             d.Duration = duration;
             return d;
         });
diff --git a/src/CarbonAware.DataSources/CarbonAware.DataSources.ElectricityMaps/test/Client/ElectricityMapsClientTests.cs b/src/CarbonAware.DataSources/CarbonAware.DataSources.ElectricityMaps/test/Client/ElectricityMapsClientTests.cs
index 6afd06ece..27ce86897 100644
--- a/src/CarbonAware.DataSources/CarbonAware.DataSources.ElectricityMaps/test/Client/ElectricityMapsClientTests.cs
+++ b/src/CarbonAware.DataSources/CarbonAware.DataSources.ElectricityMaps/test/Client/ElectricityMapsClientTests.cs
@@ -53,8 +53,8 @@ public void ClientInstantiation_FailsForInvalidConfig(string baseUrl)
         CreateBasicClient(TestData.GetZonesAllowedJsonString(), "{}");
         this.Configuration = new ElectricityMapsClientConfiguration()
         {
-            APITokenHeader = "",
-            APIToken = "",
+            APITokenHeader = string.Empty,
+            APIToken = string.Empty,
             BaseUrl = baseUrl,
         };
 
diff --git a/src/CarbonAware.Tools/CarbonAware.Tools.AWSRegionTestDataGenerator/AWSRegionTestDataGenerator.cs b/src/CarbonAware.Tools/CarbonAware.Tools.AWSRegionTestDataGenerator/AWSRegionTestDataGenerator.cs
index 7e2089938..5d8a83e0f 100644
--- a/src/CarbonAware.Tools/CarbonAware.Tools.AWSRegionTestDataGenerator/AWSRegionTestDataGenerator.cs
+++ b/src/CarbonAware.Tools/CarbonAware.Tools.AWSRegionTestDataGenerator/AWSRegionTestDataGenerator.cs
@@ -40,7 +40,7 @@ public List<EmissionsData> GenerateTestData(List<AwsRegionData> regionData)
                 var e = new EmissionsData()
                 {
                     Time = DateTime.Now + TimeSpan.FromHours(i),
-                    Location = region.code,
+                    Location = region.code ?? string.Empty,
                     Rating = ran.Next(100)
                 };
                 emData.Add(e);
diff --git a/src/CarbonAware.Tools/CarbonAware.Tools.AzureRegionTestDataGenerator/AzureRegionTestDataGenerator.cs b/src/CarbonAware.Tools/CarbonAware.Tools.AzureRegionTestDataGenerator/AzureRegionTestDataGenerator.cs
index 7294036ce..2b73ce5cb 100644
--- a/src/CarbonAware.Tools/CarbonAware.Tools.AzureRegionTestDataGenerator/AzureRegionTestDataGenerator.cs
+++ b/src/CarbonAware.Tools/CarbonAware.Tools.AzureRegionTestDataGenerator/AzureRegionTestDataGenerator.cs
@@ -44,7 +44,7 @@ public List<EmissionsData> GenerateTestData(List<AzureRegionData> regionData)
                     {
                         // 3 times per day (8 hours apart), 365 days per year 
                         Time = DateTime.Now + TimeSpan.FromHours(8 * hours) + TimeSpan.FromDays(days),
-                        Location = region.name,
+                        Location = region.name ?? string.Empty,
                         Rating = ran.Next(100)
                     };
                     emData.Add(e);
diff --git a/src/CarbonAware/src/CarbonAware.csproj b/src/CarbonAware/src/CarbonAware.csproj
index c9b44a377..0726af7c4 100644
--- a/src/CarbonAware/src/CarbonAware.csproj
+++ b/src/CarbonAware/src/CarbonAware.csproj
@@ -2,6 +2,7 @@
 
   <PropertyGroup>
     <TargetFramework>net6.0</TargetFramework>
+    <Nullable>enable</Nullable>
     <ImplicitUsings>enable</ImplicitUsings>
     <EnforceCodeStyleInBuild>true</EnforceCodeStyleInBuild>
     <IsPackable>false</IsPackable>
diff --git a/src/CarbonAware/src/CarbonAwareVariablesConfiguration.cs b/src/CarbonAware/src/CarbonAwareVariablesConfiguration.cs
index 811bc7a00..8556dcdcd 100644
--- a/src/CarbonAware/src/CarbonAwareVariablesConfiguration.cs
+++ b/src/CarbonAware/src/CarbonAwareVariablesConfiguration.cs
@@ -20,14 +20,14 @@ public class CarbonAwareVariablesConfiguration
     /// <summary>
     /// Gets or sets the forecast data source to use.
     /// </summary>
-    public string ForecastDataSource { get; set; }
+    public string ForecastDataSource { get; set; } = string.Empty;
 
     /// <summary>
     /// Gets or sets the emissions data source to use.
     /// </summary>
-    public string EmissionsDataSource { get; set; }
+    public string EmissionsDataSource { get; set; } = string.Empty;
 
-    #nullable enable
+#nullable enable
     /// <summary>
     /// Gets or sets proxy information for making calls to the internet.
     /// </summary>
diff --git a/src/CarbonAware/src/Extensions/EmissionsDataExtensions.cs b/src/CarbonAware/src/Extensions/EmissionsDataExtensions.cs
index 5cc0e0cb4..70ef4bd12 100644
--- a/src/CarbonAware/src/Extensions/EmissionsDataExtensions.cs
+++ b/src/CarbonAware/src/Extensions/EmissionsDataExtensions.cs
@@ -48,7 +48,7 @@ public static IEnumerable<EmissionsData> RollingAverage(this IEnumerable<Emissio
         var _data = data.GetEnumerator();
         _data.MoveNext();
         EmissionsData current = _data.Current;
-        EmissionsData last = null;
+        EmissionsData? last = null;
 
         if (tickSize == default)
         {
@@ -151,7 +151,7 @@ public static double AverageOverPeriod(this IEnumerable<EmissionsData> data, Dat
     {
         double rating = 0.0;
         TimeSpan totalDuration = endTime - startTime;
-        EmissionsData previous = null;
+        EmissionsData? previous = null;
         (bool reverseChronology, bool emptyEnumerable) = GetChronologyDetails(data);
         bool startTimeCoverage = false;
         bool endTimeCoverage = false;
@@ -193,8 +193,8 @@ public static double AverageOverPeriod(this IEnumerable<EmissionsData> data, Dat
 
     private static (bool reverseChronology, bool emptyEnumerable) GetChronologyDetails(IEnumerable<EmissionsData> data)
     {
-        EmissionsData current = null;
-        EmissionsData next = null;
+        EmissionsData? current = null;
+        EmissionsData? next = null;
         var _data = data.GetEnumerator();
 
         if (_data.MoveNext())
diff --git a/src/CarbonAware/src/Model/EmissionsData.cs b/src/CarbonAware/src/Model/EmissionsData.cs
index 06561623b..b17cef086 100644
--- a/src/CarbonAware/src/Model/EmissionsData.cs
+++ b/src/CarbonAware/src/Model/EmissionsData.cs
@@ -4,7 +4,7 @@
 public record EmissionsData
 {
     ///<example> eastus </example>
-    public string Location { get; set; }
+    public string Location { get; set; } = string.Empty;
     ///<example> 01-01-2022 </example>   
     public DateTimeOffset Time { get; set; }
     ///<example> 140.5 </example>
diff --git a/src/CarbonAware/src/Model/EmissionsForecast.cs b/src/CarbonAware/src/Model/EmissionsForecast.cs
index b6a9f8a16..913fe415d 100644
--- a/src/CarbonAware/src/Model/EmissionsForecast.cs
+++ b/src/CarbonAware/src/Model/EmissionsForecast.cs
@@ -41,7 +41,7 @@ public record EmissionsForecast
     /// <summary>
     /// Gets or sets the optimal data points within the ForecastData set.
     /// </summary>
-    public IEnumerable<EmissionsData> OptimalDataPoints { get; set; }
+    public IEnumerable<EmissionsData> OptimalDataPoints { get; set; } = new List<EmissionsData>();
 
 
     public void Validate()
diff --git a/src/CarbonAware/src/WebProxyConfiguration.cs b/src/CarbonAware/src/WebProxyConfiguration.cs
index 6c5951457..355454f17 100644
--- a/src/CarbonAware/src/WebProxyConfiguration.cs
+++ b/src/CarbonAware/src/WebProxyConfiguration.cs
@@ -11,15 +11,15 @@ public class WebProxyConfiguration
     /// <summary>
     /// Gets or sets the proxy url
     /// </summary>
-    public string Url { get; set; }
+    public string Url { get; set; } = string.Empty;
 
     /// <summary>
     /// Sets the proxy username
     /// </summary>
-    public string Username { get; set; }
+    public string Username { get; set; } = string.Empty;
 
     /// <summary>
     /// Sets the proxy password
     /// </summary>
-    public string Password { get; set; }
+    public string Password { get; set; } = string.Empty;
 }