diff --git a/CHANGELOG.md b/CHANGELOG.md
index 04c1a7f..f9f7952 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -8,6 +8,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 
 ### Changed
  - Fixed JSON DateTime parsing in .Net Standard
+ - Fixed threading exception in TypeExtensions
 
 ## [9.4.0] - 2019-05-10
 ### Added
diff --git a/ICD.Common.Utils/Extensions/TypeExtensions.cs b/ICD.Common.Utils/Extensions/TypeExtensions.cs
index 706bd5d..685dd65 100644
--- a/ICD.Common.Utils/Extensions/TypeExtensions.cs
+++ b/ICD.Common.Utils/Extensions/TypeExtensions.cs
@@ -369,7 +369,7 @@ namespace ICD.Common.Utils.Extensions
 						: extends.FullName;
 				}
 
-				s_TypeToMinimalName.Add(extends, name);
+				s_TypeToMinimalName[extends] = name;
 			}
 
 			return name;
@@ -389,7 +389,7 @@ namespace ICD.Common.Utils.Extensions
 			if (!s_TypeToNameWithoutAssemblyDetails.TryGetValue(extends, out name))
 			{
 				name = RemoveAssemblyDetails(extends.AssemblyQualifiedName);
-				s_TypeToNameWithoutAssemblyDetails.Add(extends, name);
+				s_TypeToNameWithoutAssemblyDetails[extends] = name;
 			}
 
 			return name;