diff --git a/src/main/java/io/github/sskorol/core/DataProviderTransformer.java b/src/main/java/io/github/sskorol/core/DataProviderTransformer.java
index 97b60b0..70a3144 100755
--- a/src/main/java/io/github/sskorol/core/DataProviderTransformer.java
+++ b/src/main/java/io/github/sskorol/core/DataProviderTransformer.java
@@ -44,8 +44,8 @@ private DataSupplierMetaData getMetaData(final ITestContext context, final ITest
     }
 
     @SuppressWarnings("FinalLocalVariable")
-    private void assignCustomDataSupplier(final IDataProvidable annotation, final Method testMethod,
-                                          final Class testClass) {
+    private <T> void assignCustomDataSupplier(final IDataProvidable annotation, final Method testMethod,
+                                              final Class<T> testClass) {
         var dataSupplierClass = getDataSupplierClass(annotation, testClass, testMethod);
         var dataSupplierAnnotation = getDataSupplierAnnotation(dataSupplierClass, annotation.getDataProvider());
 
diff --git a/src/main/java/io/github/sskorol/core/IAnnotationTransformerInterceptor.java b/src/main/java/io/github/sskorol/core/IAnnotationTransformerInterceptor.java
index e01e213..d75a029 100644
--- a/src/main/java/io/github/sskorol/core/IAnnotationTransformerInterceptor.java
+++ b/src/main/java/io/github/sskorol/core/IAnnotationTransformerInterceptor.java
@@ -11,8 +11,8 @@
  */
 public interface IAnnotationTransformerInterceptor {
 
-    default void transform(final ITestAnnotation annotation, final Class testClass,
-                           final Constructor testConstructor, final Method testMethod) {
+    default <T> void transform(final ITestAnnotation annotation, final Class<T> testClass,
+                               final Constructor<T> testConstructor, final Method testMethod) {
         // not implemented
     }
 
@@ -20,8 +20,8 @@ default void transform(final IFactoryAnnotation annotation, final Method testMet
         // not implemented
     }
 
-    default void transform(final IConfigurationAnnotation annotation, final Class testClass,
-                           final Constructor testConstructor, final Method testMethod) {
+    default <T> void transform(final IConfigurationAnnotation annotation, final Class<T> testClass,
+                               final Constructor<T> testConstructor, final Method testMethod) {
         // not implemented
     }
 
@@ -29,7 +29,7 @@ default void transform(final IDataProviderAnnotation annotation, final Method me
         // not implemented
     }
 
-    default void transform(final IListenersAnnotation annotation, final Class testClass) {
+    default <T> void transform(final IListenersAnnotation annotation, final Class<T> testClass) {
         // not implemented
     }
 }
diff --git a/src/main/java/io/github/sskorol/utils/ReflectionUtils.java b/src/main/java/io/github/sskorol/utils/ReflectionUtils.java
index 06483d6..d4bf28f 100644
--- a/src/main/java/io/github/sskorol/utils/ReflectionUtils.java
+++ b/src/main/java/io/github/sskorol/utils/ReflectionUtils.java
@@ -37,8 +37,9 @@
 @UtilityClass
 public class ReflectionUtils {
 
-    public static Class<?> getDataSupplierClass(final IDataProvidable annotation, final Class testClass,
-                                                final Method testMethod) {
+    @SuppressWarnings("unchecked")
+    public static <T> Class<T> getDataSupplierClass(final IDataProvidable annotation, final Class<T> testClass,
+                                                    final Method testMethod) {
         return ofNullable(annotation.getDataProviderClass())
                 .map(dataProviderClass -> (Class) dataProviderClass)
                 .orElseGet(() -> findParentDataSupplierClass(testMethod, testClass));
@@ -148,8 +149,9 @@ private static Tuple2<Class<?>, String> getFactoryAnnotationMetaData(final ITest
         return Tuple.of(dataProviderClass, dataProviderMethod);
     }
 
-    private static Class<?> findParentDataSupplierClass(final Method testMethod, final Class testClass) {
-        return ofNullable(testMethod)
+    @SuppressWarnings("unchecked")
+    private static <T> Class<T> findParentDataSupplierClass(final Method testMethod, final Class<T> testClass) {
+        return (Class<T>) ofNullable(testMethod)
                 .map(m -> Tuple.of(m, new Reflections(m.getDeclaringClass().getPackage().getName())))
                 .map(findParentDataSupplierClass())
                 .orElse(testClass);