diff --git a/engine/src/main/java/net/jqwik/engine/support/GenericsClassContext.java b/engine/src/main/java/net/jqwik/engine/support/GenericsClassContext.java
index 8f6b6df47..a8952bbf7 100644
--- a/engine/src/main/java/net/jqwik/engine/support/GenericsClassContext.java
+++ b/engine/src/main/java/net/jqwik/engine/support/GenericsClassContext.java
@@ -5,8 +5,6 @@
 import java.util.*;
 import java.util.stream.*;
 
-import net.jqwik.api.providers.*;
-
 public class GenericsClassContext {
 
 	static final GenericsClassContext NULL = new GenericsClassContext(null) {
@@ -16,15 +14,15 @@ public String toString() {
 		}
 	};
 
-	private final TypeUsage contextType;
+	private final Class<?> contextClass;
 	private final Map<LookupTypeVariable, TypeResolution> resolutions = new LinkedHashMap<>();
 
-	GenericsClassContext(TypeUsage contextType) {
-		this.contextType = contextType;
+	GenericsClassContext(Class<?> contextClass) {
+		this.contextClass = contextClass;
 	}
 
-	public TypeUsage contextType() {
-		return contextType;
+	public Class<?> contextClass() {
+		return contextClass;
 	}
 
 	void addResolution(TypeVariable typeVariable, Type resolvedType, AnnotatedType annotatedType) {
@@ -34,7 +32,7 @@ void addResolution(TypeVariable typeVariable, Type resolvedType, AnnotatedType a
 
 	@Override
 	public String toString() {
-		return String.format("GenericsContext(%s)", contextType.toString());
+		return String.format("GenericsContext(%s)", contextClass);
 	}
 
 	public TypeResolution resolveParameter(Parameter parameter) {
@@ -102,7 +100,7 @@ public AnnotatedType[] getAnnotatedActualTypeArguments() {
 	private TypeResolution resolveVariable(TypeResolution typeVariableResolution) {
 		TypeResolution localResolution = resolveVariableLocally(typeVariableResolution);
 		if (localResolution.isVariable()) {
-			TypeResolution supertypeResolution = resolveVariableInSupertypesOf(localResolution, contextType);
+			TypeResolution supertypeResolution = resolveVariableInSupertypesOf(localResolution, contextClass);
 			if (supertypeResolution.typeHasChanged()) {
 				return resolveType(supertypeResolution);
 			}
@@ -119,19 +117,29 @@ private TypeResolution resolveVariableLocally(TypeResolution typeResolution) {
 		return resolutions.getOrDefault(variable, typeResolution.unchanged());
 	}
 
-	private static TypeResolution resolveVariableInSupertypesOf(TypeResolution variableResolution, TypeUsage type) {
-		return resolveVariableInTypes(variableResolution, type.getSuperTypes());
+	private static TypeResolution resolveVariableInSupertypesOf(TypeResolution variableResolution, Class<?> clazz) {
+		return resolveVariableInTypes(variableResolution, supertypesOf(clazz));
+	}
+
+	private static Collection<Class<?>> supertypesOf(Class<?> clazz) {
+		if (clazz == null) {
+			return Collections.emptySet();
+		}
+		Set<Class<?>> supertypes = new LinkedHashSet<>();
+		supertypes.add(clazz.getSuperclass());
+		supertypes.addAll(Arrays.asList(clazz.getInterfaces()));
+		return supertypes;
 	}
 
-	private static TypeResolution resolveVariableInTypes(TypeResolution variableResolution, Collection<TypeUsage> superTypes) {
-		for (TypeUsage superType : superTypes) {
+	private static TypeResolution resolveVariableInTypes(TypeResolution variableResolution, Collection<Class<?>> superTypes) {
+		for (Class<?> superType : superTypes) {
 			GenericsClassContext context = GenericsSupport.contextFor(superType);
 			TypeResolution resolved = context.resolveVariableLocally(variableResolution);
 			if (resolved.typeHasChanged()) {
 				return resolved;
 			}
 		}
-		for (TypeUsage superType : superTypes) {
+		for (Class<?> superType : superTypes) {
 			TypeResolution typeResolution = resolveVariableInSupertypesOf(variableResolution, superType);
 			if (typeResolution.typeHasChanged()) {
 				return typeResolution;
diff --git a/engine/src/main/java/net/jqwik/engine/support/GenericsSupport.java b/engine/src/main/java/net/jqwik/engine/support/GenericsSupport.java
index d6697eec1..882fc8b0a 100644
--- a/engine/src/main/java/net/jqwik/engine/support/GenericsSupport.java
+++ b/engine/src/main/java/net/jqwik/engine/support/GenericsSupport.java
@@ -29,17 +29,18 @@ public synchronized static GenericsClassContext contextFor(TypeUsage typeUsage)
 	}
 
 	private static GenericsClassContext createContext(TypeUsage typeUsage) {
-		GenericsClassContext context = new GenericsClassContext(typeUsage);
+		Class<?> contextClass = typeUsage.getRawType();
+		GenericsClassContext context = new GenericsClassContext(contextClass);
 		addOwnResolutions(typeUsage, context);
-		addResolutionsForSuperclass(typeUsage, context);
-		addResolutionsForInterfaces(typeUsage, context);
+		addResolutionsForSuperclass(context);
+		addResolutionsForInterfaces(context);
 		return context;
 	}
 
-	private static void addResolutionsForInterfaces(TypeUsage contextType, GenericsClassContext context) {
-		Class<?>[] interfaces = contextType.getRawType().getInterfaces();
-		Type[] genericInterfaces = contextType.getRawType().getGenericInterfaces();
-		AnnotatedType[] annotatedInterfaces = contextType.getRawType().getAnnotatedInterfaces();
+	private static void addResolutionsForInterfaces(GenericsClassContext context) {
+		Class<?>[] interfaces = context.contextClass().getInterfaces();
+		Type[] genericInterfaces = context.contextClass().getGenericInterfaces();
+		AnnotatedType[] annotatedInterfaces = context.contextClass().getAnnotatedInterfaces();
 		for (int i = 0; i < interfaces.length; i++) {
 			Class<?> supertype = interfaces[i];
 			Type genericSupertype = genericInterfaces[i];
@@ -48,11 +49,11 @@ private static void addResolutionsForInterfaces(TypeUsage contextType, GenericsC
 		}
 	}
 
-	private static void addResolutionsForSuperclass(TypeUsage typeUsage, GenericsClassContext context) {
+	private static void addResolutionsForSuperclass(GenericsClassContext context) {
 		addResolutionsForSupertype(
-			typeUsage.getRawType().getSuperclass(),
-			typeUsage.getRawType().getGenericSuperclass(),
-			typeUsage.getRawType().getAnnotatedSuperclass(),
+			context.contextClass().getSuperclass(),
+			context.contextClass().getGenericSuperclass(),
+			context.contextClass().getAnnotatedSuperclass(),
 			context
 		);
 	}
diff --git a/engine/src/test/java/net/jqwik/engine/support/GenericsSupportTests.java b/engine/src/test/java/net/jqwik/engine/support/GenericsSupportTests.java
index d8d6e8d4d..f4f61bb3e 100644
--- a/engine/src/test/java/net/jqwik/engine/support/GenericsSupportTests.java
+++ b/engine/src/test/java/net/jqwik/engine/support/GenericsSupportTests.java
@@ -25,7 +25,7 @@ public Integer apply(String s) {
 		}
 
 		GenericsClassContext context = GenericsSupport.contextFor(JustAClass.class);
-		assertThat(context.contextType().getRawType()).isSameAs(JustAClass.class);
+		assertThat(context.contextClass()).isSameAs(JustAClass.class);
 	}
 
 	private interface PartialFunction<T> extends Function<T, String> {}
@@ -36,7 +36,7 @@ void createContextFromTypeUsage() throws NoSuchMethodException {
 			TypeUsage.of(PartialFunction.class, TypeUsage.of(Integer.class));
 
 		GenericsClassContext context = GenericsSupport.contextFor(integerToStringFunction);
-		assertThat(context.contextType()).isSameAs(integerToStringFunction);
+		assertThat(context.contextClass()).isSameAs(PartialFunction.class);
 
 		Method functionMethod = Function.class.getMethod("apply", Object.class);