diff --git a/src/NuGetForUnity.Tests/Assets/Tests/Resources/NuGet.config b/src/NuGetForUnity.Tests/Assets/Tests/Resources/NuGet.config
index 97f21355..8362190c 100644
--- a/src/NuGetForUnity.Tests/Assets/Tests/Resources/NuGet.config
+++ b/src/NuGetForUnity.Tests/Assets/Tests/Resources/NuGet.config
@@ -15,9 +15,10 @@
     <add key="All" value="(Aggregate source)" />
   </activePackageSource>
   <config>
+    <add key="packageInstallLocation" value="CustomWithinAssets" />
     <add key="repositoryPath" value="./Packages" />
     <add key="PackagesConfigDirectoryPath" value="." />
     <add key="slimRestore" value="true" />
-    <add key="ReadOnlyPackageFiles" value="false" />
+    <add key="PreferNetStandardOverNetFramework" value="true" />
   </config>
 </configuration>
\ No newline at end of file
diff --git a/src/NuGetForUnity/Editor/NugetPackageInstaller.cs b/src/NuGetForUnity/Editor/NugetPackageInstaller.cs
index 9fd20529..41756a91 100644
--- a/src/NuGetForUnity/Editor/NugetPackageInstaller.cs
+++ b/src/NuGetForUnity/Editor/NugetPackageInstaller.cs
@@ -24,8 +24,13 @@ public static class NugetPackageInstaller
         /// <param name="package">The identifier of the package to install.</param>
         /// <param name="refreshAssets">True to refresh the Unity asset database.  False to ignore the changes (temporarily).</param>
         /// <param name="isSlimRestoreInstall">True to skip checking if lib is imported in Unity and skip installing dependencies.</param>
+        /// <param name="allowUpdateForExplicitlyInstalled">False to prevent updating of packages that are explicitly installed.</param>
         /// <returns>True if the package was installed successfully, otherwise false.</returns>
-        public static bool InstallIdentifier([NotNull] INugetPackageIdentifier package, bool refreshAssets = true, bool isSlimRestoreInstall = false)
+        public static bool InstallIdentifier(
+            [NotNull] INugetPackageIdentifier package,
+            bool refreshAssets = true,
+            bool isSlimRestoreInstall = false,
+            bool allowUpdateForExplicitlyInstalled = true)
         {
             if (!isSlimRestoreInstall && UnityPreImportedLibraryResolver.IsAlreadyImportedInEngine(package.Id, false))
             {
@@ -42,7 +47,7 @@ public static bool InstallIdentifier([NotNull] INugetPackageIdentifier package,
             }
 
             foundPackage.IsManuallyInstalled = package.IsManuallyInstalled;
-            return Install(foundPackage, refreshAssets, isSlimRestoreInstall);
+            return Install(foundPackage, refreshAssets, isSlimRestoreInstall, allowUpdateForExplicitlyInstalled);
         }
 
         /// <summary>
@@ -51,8 +56,13 @@ public static bool InstallIdentifier([NotNull] INugetPackageIdentifier package,
         /// <param name="package">The package to install.</param>
         /// <param name="refreshAssets">True to refresh the Unity asset database.  False to ignore the changes (temporarily).</param>
         /// <param name="isSlimRestoreInstall">True to skip checking if lib is imported in Unity and skip installing dependencies.</param>
+        /// <param name="allowUpdateForExplicitlyInstalled">False to prevent updating of packages that are explicitly installed.</param>
         /// <returns>True if the package was installed successfully, otherwise false.</returns>
-        private static bool Install([NotNull] INugetPackage package, bool refreshAssets, bool isSlimRestoreInstall)
+        private static bool Install(
+            [NotNull] INugetPackage package,
+            bool refreshAssets,
+            bool isSlimRestoreInstall,
+            bool allowUpdateForExplicitlyInstalled)
         {
             if (!isSlimRestoreInstall && UnityPreImportedLibraryResolver.IsAlreadyImportedInEngine(package.Id, false))
             {
@@ -64,6 +74,18 @@ private static bool Install([NotNull] INugetPackage package, bool refreshAssets,
             if (InstalledPackagesManager.TryGetById(package.Id, out var installedPackage))
             {
                 var comparisonResult = installedPackage.CompareTo(package);
+
+                if (!allowUpdateForExplicitlyInstalled && comparisonResult != 0 && installedPackage.IsManuallyInstalled)
+                {
+                    NugetLogger.LogVerbose(
+                        "{0} {1} is installed explicitly so it will not be replaced with {3}",
+                        installedPackage.Id,
+                        installedPackage.Version,
+                        package.Version,
+                        package.Version);
+                    return true;
+                }
+
                 if (comparisonResult < 0)
                 {
                     NugetLogger.LogVerbose(
@@ -131,7 +153,7 @@ private static bool Install([NotNull] INugetPackage package, bool refreshAssets,
                         foreach (var dependency in frameworkGroup.Dependencies)
                         {
                             NugetLogger.LogVerbose("Installing Dependency: {0} {1}", dependency.Id, dependency.Version);
-                            var installed = InstallIdentifier(dependency, false);
+                            var installed = InstallIdentifier(dependency, false, false, false);
                             if (!installed)
                             {
                                 throw new InvalidOperationException($"Failed to install dependency: {dependency.Id} {dependency.Version}.");