diff --git a/src/FluentAssertions.Analyzers.Tests/Tips/SanityTests.cs b/src/FluentAssertions.Analyzers.Tests/Tips/SanityTests.cs
index 443df1c7..ae5b2933 100644
--- a/src/FluentAssertions.Analyzers.Tests/Tips/SanityTests.cs
+++ b/src/FluentAssertions.Analyzers.Tests/Tips/SanityTests.cs
@@ -160,5 +160,34 @@ public void StringShouldNotBeEmptyAndShouldNotBeNull_ShouldNotTrigger()
 
             DiagnosticVerifier.VerifyCSharpDiagnosticUsingAllAnalyzers(source);
         }
+
+        [TestMethod]
+        [Implemented(Reason = "https://github.com/fluentassertions/fluentassertions.analyzers/issues/65")]
+        public void CustomClass_ShouldNotTrigger_DictionaryAnalyzers()
+        {
+            const string source = @"
+using System.Linq;
+using FluentAssertions;
+using FluentAssertions.Extensions;
+
+namespace TestNamespace
+{
+    class MyDict<TKey, TValue>
+    {
+        public bool ContainsKey(TKey key) => false;
+    }
+    
+    public class Program
+    {
+        public static void Main()
+        {
+            var dict = new MyDict<int, string>();
+            dict.ContainsKey(0).Should().BeTrue();
+        }
+    }
+}";
+
+            DiagnosticVerifier.VerifyCSharpDiagnosticUsingAllAnalyzers(source);
+        }
     }
 }
\ No newline at end of file
diff --git a/src/FluentAssertions.Analyzers/Tips/Dictionaries/DictionaryAnalyzer.cs b/src/FluentAssertions.Analyzers/Tips/Dictionaries/DictionaryAnalyzer.cs
new file mode 100644
index 00000000..910c5b06
--- /dev/null
+++ b/src/FluentAssertions.Analyzers/Tips/Dictionaries/DictionaryAnalyzer.cs
@@ -0,0 +1,11 @@
+using System.Linq;
+using Microsoft.CodeAnalysis;
+
+namespace FluentAssertions.Analyzers
+{
+    public abstract class DictionaryAnalyzer : FluentAssertionsAnalyzer
+    {
+        protected override bool ShouldAnalyzeVariableType(ITypeSymbol type)
+            => type.AllInterfaces.Any(@interface => @interface.Name == "IDictionary");
+    }
+}
\ No newline at end of file
diff --git a/src/FluentAssertions.Analyzers/Tips/Dictionaries/DictionaryShouldContainKey.cs b/src/FluentAssertions.Analyzers/Tips/Dictionaries/DictionaryShouldContainKey.cs
index 4f52e8c6..12bffffe 100644
--- a/src/FluentAssertions.Analyzers/Tips/Dictionaries/DictionaryShouldContainKey.cs
+++ b/src/FluentAssertions.Analyzers/Tips/Dictionaries/DictionaryShouldContainKey.cs
@@ -9,7 +9,7 @@
 namespace FluentAssertions.Analyzers
 {
     [DiagnosticAnalyzer(LanguageNames.CSharp)]
-    public class DictionaryShouldContainKeyAnalyzer : FluentAssertionsAnalyzer
+    public class DictionaryShouldContainKeyAnalyzer : DictionaryAnalyzer
     {
         public const string DiagnosticId = Constants.Tips.Dictionaries.DictionaryShouldContainKey;
         public const string Category = Constants.Tips.Category;
diff --git a/src/FluentAssertions.Analyzers/Tips/Dictionaries/DictionaryShouldContainKeyAndValue.cs b/src/FluentAssertions.Analyzers/Tips/Dictionaries/DictionaryShouldContainKeyAndValue.cs
index 75a64b3e..e4f4a48c 100644
--- a/src/FluentAssertions.Analyzers/Tips/Dictionaries/DictionaryShouldContainKeyAndValue.cs
+++ b/src/FluentAssertions.Analyzers/Tips/Dictionaries/DictionaryShouldContainKeyAndValue.cs
@@ -10,7 +10,7 @@
 namespace FluentAssertions.Analyzers
 {
     [DiagnosticAnalyzer(LanguageNames.CSharp)]
-    public class DictionaryShouldContainKeyAndValueAnalyzer : FluentAssertionsAnalyzer
+    public class DictionaryShouldContainKeyAndValueAnalyzer : DictionaryAnalyzer
     {
         public const string DiagnosticId = Constants.Tips.Dictionaries.DictionaryShouldContainKeyAndValue;
         public const string Category = Constants.Tips.Category;
diff --git a/src/FluentAssertions.Analyzers/Tips/Dictionaries/DictionaryShouldContainPair.cs b/src/FluentAssertions.Analyzers/Tips/Dictionaries/DictionaryShouldContainPair.cs
index cd0ab10c..1b909307 100644
--- a/src/FluentAssertions.Analyzers/Tips/Dictionaries/DictionaryShouldContainPair.cs
+++ b/src/FluentAssertions.Analyzers/Tips/Dictionaries/DictionaryShouldContainPair.cs
@@ -10,7 +10,7 @@
 namespace FluentAssertions.Analyzers
 {
     [DiagnosticAnalyzer(LanguageNames.CSharp)]
-    public class DictionaryShouldContainPairAnalyzer : FluentAssertionsAnalyzer
+    public class DictionaryShouldContainPairAnalyzer : DictionaryAnalyzer
     {
         public const string DiagnosticId = Constants.Tips.Dictionaries.DictionaryShouldContainPair;
         public const string Category = Constants.Tips.Category;
diff --git a/src/FluentAssertions.Analyzers/Tips/Dictionaries/DictionaryShouldContainValue.cs b/src/FluentAssertions.Analyzers/Tips/Dictionaries/DictionaryShouldContainValue.cs
index e0061bb2..eac96ec3 100644
--- a/src/FluentAssertions.Analyzers/Tips/Dictionaries/DictionaryShouldContainValue.cs
+++ b/src/FluentAssertions.Analyzers/Tips/Dictionaries/DictionaryShouldContainValue.cs
@@ -9,7 +9,7 @@
 namespace FluentAssertions.Analyzers
 {
     [DiagnosticAnalyzer(LanguageNames.CSharp)]
-    public class DictionaryShouldContainValueAnalyzer : FluentAssertionsAnalyzer
+    public class DictionaryShouldContainValueAnalyzer : DictionaryAnalyzer
     {
         public const string DiagnosticId = Constants.Tips.Dictionaries.DictionaryShouldContainValue;
         public const string Category = Constants.Tips.Category;
diff --git a/src/FluentAssertions.Analyzers/Tips/Dictionaries/DictionaryShouldNotContainKey.cs b/src/FluentAssertions.Analyzers/Tips/Dictionaries/DictionaryShouldNotContainKey.cs
index 19bfe69d..f09275fb 100644
--- a/src/FluentAssertions.Analyzers/Tips/Dictionaries/DictionaryShouldNotContainKey.cs
+++ b/src/FluentAssertions.Analyzers/Tips/Dictionaries/DictionaryShouldNotContainKey.cs
@@ -9,7 +9,7 @@
 namespace FluentAssertions.Analyzers
 {
     [DiagnosticAnalyzer(LanguageNames.CSharp)]
-    public class DictionaryShouldNotContainKeyAnalyzer : FluentAssertionsAnalyzer
+    public class DictionaryShouldNotContainKeyAnalyzer : DictionaryAnalyzer
     {
         public const string DiagnosticId = Constants.Tips.Dictionaries.DictionaryShouldNotContainKey;
         public const string Category = Constants.Tips.Category;
diff --git a/src/FluentAssertions.Analyzers/Tips/Dictionaries/DictionaryShouldNotContainValue.cs b/src/FluentAssertions.Analyzers/Tips/Dictionaries/DictionaryShouldNotContainValue.cs
index b7e388e8..421ac5bf 100644
--- a/src/FluentAssertions.Analyzers/Tips/Dictionaries/DictionaryShouldNotContainValue.cs
+++ b/src/FluentAssertions.Analyzers/Tips/Dictionaries/DictionaryShouldNotContainValue.cs
@@ -9,7 +9,7 @@
 namespace FluentAssertions.Analyzers
 {
     [DiagnosticAnalyzer(LanguageNames.CSharp)]
-    public class DictionaryShouldNotContainValueAnalyzer : FluentAssertionsAnalyzer
+    public class DictionaryShouldNotContainValueAnalyzer : DictionaryAnalyzer
     {
         public const string DiagnosticId = Constants.Tips.Dictionaries.DictionaryShouldNotContainValue;
         public const string Category = Constants.Tips.Category;
diff --git a/src/FluentAssertions.Analyzers/Utilities/FluentAssertionsAnalyzer.cs b/src/FluentAssertions.Analyzers/Utilities/FluentAssertionsAnalyzer.cs
index 7a84bb51..4ab1e79f 100644
--- a/src/FluentAssertions.Analyzers/Utilities/FluentAssertionsAnalyzer.cs
+++ b/src/FluentAssertions.Analyzers/Utilities/FluentAssertionsAnalyzer.cs
@@ -60,8 +60,8 @@ protected virtual Diagnostic AnalyzeExpression(ExpressionSyntax expression, Sema
 
             if (variableNameExtractor.VariableIdentifierName == null) return null;
             var typeInfo = semanticModel.GetTypeInfo(variableNameExtractor.VariableIdentifierName);
-            if (typeInfo.ConvertedType == null) return null;
-            if (!ShouldAnalyzeVariableType(typeInfo.ConvertedType)) return null;
+            if (typeInfo.Type == null) return null;
+            if (!ShouldAnalyzeVariableType(typeInfo.Type)) return null;
 
             foreach (var visitor in Visitors)
             {