diff --git a/sonaranalyzer-dotnet/its/expected/Nancy/Nancy-{34576216-0DCA-4B0F-A0DC-9075E75A676F}-S4226.json b/sonaranalyzer-dotnet/its/expected/Nancy/Nancy-{34576216-0DCA-4B0F-A0DC-9075E75A676F}-S4226.json
index 4b4adb77c5c..ec02798d210 100644
--- a/sonaranalyzer-dotnet/its/expected/Nancy/Nancy-{34576216-0DCA-4B0F-A0DC-9075E75A676F}-S4226.json
+++ b/sonaranalyzer-dotnet/its/expected/Nancy/Nancy-{34576216-0DCA-4B0F-A0DC-9075E75A676F}-S4226.json
@@ -4,71 +4,6 @@
 "id":  "S4226",
 "message":  "Either move this extension to another namespace or move the method inside the type itself.",
 "location":  {
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-{
-"id":  "S4226",
-"message":  "Either move this extension to another namespace or move the method inside the type itself.",
-"location":  {
-"uri":  "sources\Nancy\src\Nancy\Configuration\INancyEnvironmentExtensions.cs",
-"region":  {
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-{
-"id":  "S4226",
-"message":  "Either move this extension to another namespace or move the method inside the type itself.",
-"location":  {
-"uri":  "sources\Nancy\src\Nancy\Configuration\INancyEnvironmentExtensions.cs",
-"region":  {
-"startLine":  39,
-"startColumn":  25,
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-{
-"id":  "S4226",
-"message":  "Either move this extension to another namespace or move the method inside the type itself.",
-"location":  {
-"uri":  "sources\Nancy\src\Nancy\Configuration\INancyEnvironmentExtensions.cs",
-"region":  {
-"startLine":  52,
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-}
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-{
-"id":  "S4226",
-"message":  "Either move this extension to another namespace or move the method inside the type itself.",
-"location":  {
-"uri":  "sources\Nancy\src\Nancy\Configuration\INancyEnvironmentExtensions.cs",
-"region":  {
-"startLine":  67,
-"startColumn":  25,
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-{
-"id":  "S4226",
-"message":  "Either move this extension to another namespace or move the method inside the type itself.",
-"location":  {
 "uri":  "sources\Nancy\src\Nancy\Conventions\StaticContentHelper.cs",
 "region":  {
 "startLine":  22,
@@ -82,162 +17,6 @@
 "id":  "S4226",
 "message":  "Either move this extension to another namespace or move the method inside the type itself.",
 "location":  {
-"uri":  "sources\Nancy\src\Nancy\FormatterExtensions.cs",
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-"startLine":  25,
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-{
-"id":  "S4226",
-"message":  "Either move this extension to another namespace or move the method inside the type itself.",
-"location":  {
-"uri":  "sources\Nancy\src\Nancy\FormatterExtensions.cs",
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-"startLine":  37,
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-}
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-{
-"id":  "S4226",
-"message":  "Either move this extension to another namespace or move the method inside the type itself.",
-"location":  {
-"uri":  "sources\Nancy\src\Nancy\FormatterExtensions.cs",
-"region":  {
-"startLine":  51,
-"startColumn":  32,
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-}
-}
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-{
-"id":  "S4226",
-"message":  "Either move this extension to another namespace or move the method inside the type itself.",
-"location":  {
-"uri":  "sources\Nancy\src\Nancy\FormatterExtensions.cs",
-"region":  {
-"startLine":  64,
-"startColumn":  32,
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-{
-"id":  "S4226",
-"message":  "Either move this extension to another namespace or move the method inside the type itself.",
-"location":  {
-"uri":  "sources\Nancy\src\Nancy\FormatterExtensions.cs",
-"region":  {
-"startLine":  76,
-"startColumn":  32,
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-}
-},
-{
-"id":  "S4226",
-"message":  "Either move this extension to another namespace or move the method inside the type itself.",
-"location":  {
-"uri":  "sources\Nancy\src\Nancy\FormatterExtensions.cs",
-"region":  {
-"startLine":  86,
-"startColumn":  32,
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-{
-"id":  "S4226",
-"message":  "Either move this extension to another namespace or move the method inside the type itself.",
-"location":  {
-"uri":  "sources\Nancy\src\Nancy\FormatterExtensions.cs",
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-"startLine":  99,
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-{
-"id":  "S4226",
-"message":  "Either move this extension to another namespace or move the method inside the type itself.",
-"location":  {
-"uri":  "sources\Nancy\src\Nancy\FormatterExtensions.cs",
-"region":  {
-"startLine":  115,
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-{
-"id":  "S4226",
-"message":  "Either move this extension to another namespace or move the method inside the type itself.",
-"location":  {
-"uri":  "sources\Nancy\src\Nancy\FormatterExtensions.cs",
-"region":  {
-"startLine":  128,
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-{
-"id":  "S4226",
-"message":  "Either move this extension to another namespace or move the method inside the type itself.",
-"location":  {
-"uri":  "sources\Nancy\src\Nancy\FormatterExtensions.cs",
-"region":  {
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-{
-"id":  "S4226",
-"message":  "Either move this extension to another namespace or move the method inside the type itself.",
-"location":  {
-"uri":  "sources\Nancy\src\Nancy\FormatterExtensions.cs",
-"region":  {
-"startLine":  154,
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-{
-"id":  "S4226",
-"message":  "Either move this extension to another namespace or move the method inside the type itself.",
-"location":  {
-"uri":  "sources\Nancy\src\Nancy\NancyEngineExtensions.cs",
-"region":  {
-"startLine":  14,
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-{
-"id":  "S4226",
-"message":  "Either move this extension to another namespace or move the method inside the type itself.",
-"location":  {
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 "region":  {
 "startLine":  16,
diff --git a/sonaranalyzer-dotnet/its/expected/akka.net/Akka-{5DEDDF90-37F0-48D3-A0B0-A5CBD8A7E377}-S4226.json b/sonaranalyzer-dotnet/its/expected/akka.net/Akka-{5DEDDF90-37F0-48D3-A0B0-A5CBD8A7E377}-S4226.json
index 2deb6b06f7e..dcfdfbe47e1 100644
--- a/sonaranalyzer-dotnet/its/expected/akka.net/Akka-{5DEDDF90-37F0-48D3-A0B0-A5CBD8A7E377}-S4226.json
+++ b/sonaranalyzer-dotnet/its/expected/akka.net/Akka-{5DEDDF90-37F0-48D3-A0B0-A5CBD8A7E377}-S4226.json
@@ -4,71 +4,6 @@
 "id":  "S4226",
 "message":  "Either move this extension to another namespace or move the method inside the type itself.",
 "location":  {
-"uri":  "sources\akka.net\src\core\Akka\Actor\ActorRef.cs",
-"region":  {
-"startLine":  122,
-"startColumn":  28,
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-{
-"id":  "S4226",
-"message":  "Either move this extension to another namespace or move the method inside the type itself.",
-"location":  {
-"uri":  "sources\akka.net\src\core\Akka\Actor\ActorRef.cs",
-"region":  {
-"startLine":  134,
-"startColumn":  28,
-"endLine":  134,
-"endColumn":  35
-}
-}
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-{
-"id":  "S4226",
-"message":  "Either move this extension to another namespace or move the method inside the type itself.",
-"location":  {
-"uri":  "sources\akka.net\src\core\Akka\Actor\ActorRef.Extensions.cs",
-"region":  {
-"startLine":  20,
-"startColumn":  28,
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-"endColumn":  36
-}
-}
-},
-{
-"id":  "S4226",
-"message":  "Either move this extension to another namespace or move the method inside the type itself.",
-"location":  {
-"uri":  "sources\akka.net\src\core\Akka\Actor\ActorRefFactoryExtensions.cs",
-"region":  {
-"startLine":  12,
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-}
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-{
-"id":  "S4226",
-"message":  "Either move this extension to another namespace or move the method inside the type itself.",
-"location":  {
-"uri":  "sources\akka.net\src\core\Akka\Actor\Cancellation\CancelableExtensions.cs",
-"region":  {
-"startLine":  16,
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-{
-"id":  "S4226",
-"message":  "Either move this extension to another namespace or move the method inside the type itself.",
-"location":  {
 "uri":  "sources\akka.net\src\core\Akka\Actor\Extensions.cs",
 "region":  {
 "startLine":  74,
@@ -108,357 +43,6 @@
 "id":  "S4226",
 "message":  "Either move this extension to another namespace or move the method inside the type itself.",
 "location":  {
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-{
-"id":  "S4226",
-"message":  "Either move this extension to another namespace or move the method inside the type itself.",
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-"region":  {
-"startLine":  32,
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-}
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-{
-"id":  "S4226",
-"message":  "Either move this extension to another namespace or move the method inside the type itself.",
-"location":  {
-"uri":  "sources\akka.net\src\core\Akka\Actor\GracefulStopSupport.cs",
-"region":  {
-"startLine":  37,
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-{
-"id":  "S4226",
-"message":  "Either move this extension to another namespace or move the method inside the type itself.",
-"location":  {
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-"region":  {
-"startLine":  42,
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-}
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-{
-"id":  "S4226",
-"message":  "Either move this extension to another namespace or move the method inside the type itself.",
-"location":  {
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-"region":  {
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-{
-"id":  "S4226",
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-"location":  {
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-"region":  {
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-{
-"id":  "S4226",
-"message":  "Either move this extension to another namespace or move the method inside the type itself.",
-"location":  {
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-"region":  {
-"startLine":  31,
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-}
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-{
-"id":  "S4226",
-"message":  "Either move this extension to another namespace or move the method inside the type itself.",
-"location":  {
-"uri":  "sources\akka.net\src\core\Akka\Actor\Scheduler\DeprecatedSchedulerExtensions.cs",
-"region":  {
-"startLine":  39,
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-}
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-{
-"id":  "S4226",
-"message":  "Either move this extension to another namespace or move the method inside the type itself.",
-"location":  {
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-{
-"id":  "S4226",
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-"location":  {
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-"region":  {
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-}
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-{
-"id":  "S4226",
-"message":  "Either move this extension to another namespace or move the method inside the type itself.",
-"location":  {
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-{
-"id":  "S4226",
-"message":  "Either move this extension to another namespace or move the method inside the type itself.",
-"location":  {
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-"region":  {
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-{
-"id":  "S4226",
-"message":  "Either move this extension to another namespace or move the method inside the type itself.",
-"location":  {
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-{
-"id":  "S4226",
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-"location":  {
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-{
-"id":  "S4226",
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-{
-"id":  "S4226",
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-"startLine":  64,
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-}
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-{
-"id":  "S4226",
-"message":  "Either move this extension to another namespace or move the method inside the type itself.",
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-{
-"id":  "S4226",
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-{
-"id":  "S4226",
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-"location":  {
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-{
-"id":  "S4226",
-"message":  "Either move this extension to another namespace or move the method inside the type itself.",
-"location":  {
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-"startLine":  122,
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-}
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-{
-"id":  "S4226",
-"message":  "Either move this extension to another namespace or move the method inside the type itself.",
-"location":  {
-"uri":  "sources\akka.net\src\core\Akka\Actor\Scheduler\SchedulerExtensions.cs",
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-}
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-{
-"id":  "S4226",
-"message":  "Either move this extension to another namespace or move the method inside the type itself.",
-"location":  {
-"uri":  "sources\akka.net\src\core\Akka\Actor\Scheduler\SchedulerExtensions.cs",
-"region":  {
-"startLine":  152,
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-}
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-{
-"id":  "S4226",
-"message":  "Either move this extension to another namespace or move the method inside the type itself.",
-"location":  {
-"uri":  "sources\akka.net\src\core\Akka\Actor\Scheduler\SchedulerExtensions.cs",
-"region":  {
-"startLine":  169,
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-{
-"id":  "S4226",
-"message":  "Either move this extension to another namespace or move the method inside the type itself.",
-"location":  {
-"uri":  "sources\akka.net\src\core\Akka\Actor\Scheduler\SchedulerExtensions.cs",
-"region":  {
-"startLine":  184,
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-}
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-{
-"id":  "S4226",
-"message":  "Either move this extension to another namespace or move the method inside the type itself.",
-"location":  {
-"uri":  "sources\akka.net\src\core\Akka\Actor\Stash\StashFactory.cs",
-"region":  {
-"startLine":  19,
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-}
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-{
-"id":  "S4226",
-"message":  "Either move this extension to another namespace or move the method inside the type itself.",
-"location":  {
-"uri":  "sources\akka.net\src\core\Akka\Actor\Stash\StashFactory.cs",
-"region":  {
-"startLine":  25,
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-"endColumn":  41
-}
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-{
-"id":  "S4226",
-"message":  "Either move this extension to another namespace or move the method inside the type itself.",
-"location":  {
-"uri":  "sources\akka.net\src\core\Akka\Actor\Stash\StashFactory.cs",
-"region":  {
-"startLine":  30,
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-}
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-{
-"id":  "S4226",
-"message":  "Either move this extension to another namespace or move the method inside the type itself.",
-"location":  {
 "uri":  "sources\akka.net\src\core\Akka\Actor\SupervisorStrategy.cs",
 "region":  {
 "startLine":  627,
@@ -576,19 +160,6 @@
 "id":  "S4226",
 "message":  "Either move this extension to another namespace or move the method inside the type itself.",
 "location":  {
-"uri":  "sources\akka.net\src\core\Akka\Util\Internal\Collections\IImmutableSet.cs",
-"region":  {
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-{
-"id":  "S4226",
-"message":  "Either move this extension to another namespace or move the method inside the type itself.",
-"location":  {
 "uri":  "sources\akka.net\src\core\Akka\Util\Internal\Extensions.cs",
 "region":  {
 "startLine":  67,
diff --git a/sonaranalyzer-dotnet/its/expected/akka.net/Akka.Cluster.Sharding-{A05C31E8-0246-46A1-B3BC-4D6FE7A9AA49}-S4226.json b/sonaranalyzer-dotnet/its/expected/akka.net/Akka.Cluster.Sharding-{A05C31E8-0246-46A1-B3BC-4D6FE7A9AA49}-S4226.json
deleted file mode 100644
index 136e7086945..00000000000
--- a/sonaranalyzer-dotnet/its/expected/akka.net/Akka.Cluster.Sharding-{A05C31E8-0246-46A1-B3BC-4D6FE7A9AA49}-S4226.json
+++ /dev/null
@@ -1,17 +0,0 @@
-{
-"issues":  [
-{
-"id":  "S4226",
-"message":  "Either move this extension to another namespace or move the method inside the type itself.",
-"location":  {
-"uri":  "sources\akka.net\src\contrib\cluster\Akka.Cluster.Sharding\ClusterSharding.cs",
-"region":  {
-"startLine":  489,
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-"endLine":  489,
-"endColumn":  48
-}
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-]
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diff --git a/sonaranalyzer-dotnet/its/expected/akka.net/Akka.Persistence.Tests-{4492004A-A8D0-45B0-BACC-05BA2F38EC55}-S4226.json b/sonaranalyzer-dotnet/its/expected/akka.net/Akka.Persistence.Tests-{4492004A-A8D0-45B0-BACC-05BA2F38EC55}-S4226.json
deleted file mode 100644
index 7ead541fa31..00000000000
--- a/sonaranalyzer-dotnet/its/expected/akka.net/Akka.Persistence.Tests-{4492004A-A8D0-45B0-BACC-05BA2F38EC55}-S4226.json
+++ /dev/null
@@ -1,17 +0,0 @@
-{
-"issues":  [
-{
-"id":  "S4226",
-"message":  "Either move this extension to another namespace or move the method inside the type itself.",
-"location":  {
-"uri":  "sources\akka.net\src\core\Akka.Persistence.Tests\AtLeastOnceDeliveryFailureSpec.cs",
-"region":  {
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-"startColumn":  30,
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-"endColumn":  33
-}
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-]
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diff --git a/sonaranalyzer-dotnet/src/SonarAnalyzer.CSharp/Rules/ExtensionMethodShouldBeInSeparateNamespace.cs b/sonaranalyzer-dotnet/src/SonarAnalyzer.CSharp/Rules/ExtensionMethodShouldBeInSeparateNamespace.cs
index eeeef7a1098..370ada4df63 100644
--- a/sonaranalyzer-dotnet/src/SonarAnalyzer.CSharp/Rules/ExtensionMethodShouldBeInSeparateNamespace.cs
+++ b/sonaranalyzer-dotnet/src/SonarAnalyzer.CSharp/Rules/ExtensionMethodShouldBeInSeparateNamespace.cs
@@ -52,6 +52,7 @@ protected override void Initialize(SonarAnalysisContext context)
                         methodSymbol.IsExtensionMethod &&
                         methodSymbol.Parameters.Length > 0 &&
                         methodSymbol.Parameters[0].Type.Kind != SymbolKind.ErrorType &&
+                        methodSymbol.Parameters[0].Type.IsClass() &&
                         methodSymbol.ContainingNamespace == methodSymbol.Parameters[0].Type.ContainingNamespace)
                     {
                         c.ReportDiagnosticWhenActive(Diagnostic.Create(rule, methodDeclaration.Identifier.GetLocation()));
diff --git a/sonaranalyzer-dotnet/tests/SonarAnalyzer.UnitTest/TestCases/ExtensionMethodShouldBeInSeparateNamespace.cs b/sonaranalyzer-dotnet/tests/SonarAnalyzer.UnitTest/TestCases/ExtensionMethodShouldBeInSeparateNamespace.cs
index 45b0971f1b3..8d3ee8f9566 100644
--- a/sonaranalyzer-dotnet/tests/SonarAnalyzer.UnitTest/TestCases/ExtensionMethodShouldBeInSeparateNamespace.cs
+++ b/sonaranalyzer-dotnet/tests/SonarAnalyzer.UnitTest/TestCases/ExtensionMethodShouldBeInSeparateNamespace.cs
@@ -48,4 +48,34 @@ static void Baz(this SomeNonExistingClass snec)
         {
         }
     }
-}
\ No newline at end of file
+}
+
+namespace OtherPackageNamespace
+{
+    public interface IFoo { }
+
+    public enum FooBar { }
+
+    public struct FooQux { }
+
+    public static class FooHelpers
+    {
+        public static void FooInterface(this IFoo foo) // Compliant
+        {
+        }
+
+        public static void FooEnum(this FooBar foo) // Compliant
+        {
+        }
+
+        public static void FooStruct(this FooQux foo) // Compliant
+        {
+        }
+
+        public static T FooGeneric<T>(this T foo) // Compliant
+        {
+            return default(T);
+        }
+    }
+
+}