diff --git a/types/clownface/clownface-tests.ts b/types/clownface/clownface-tests.ts
index 5b4264bf46..dea754b887 100644
--- a/types/clownface/clownface-tests.ts
+++ b/types/clownface/clownface-tests.ts
@@ -117,6 +117,7 @@ cf = cf.has([predicate, predicate], 'Stuart');
 cf = cf.has(predicate, [literal, literal]);
 
 // .in
+cf = cf.in();
 cf = cf.in(node);
 cf = cf.in([node, node]);
 cf = cf.in(cf.node(node));
@@ -150,6 +151,7 @@ cf = cf.node('example', { datatype: node.value });
 cf = cf.node('example', { datatype: node });
 
 // .out
+cf = cf.out();
 cf = cf.out(node);
 cf = cf.out([node, node]);
 cf = cf.out(cf.node([node, node]));
diff --git a/types/clownface/index.d.ts b/types/clownface/index.d.ts
index e7ef50f1a9..f4a2744e4b 100644
--- a/types/clownface/index.d.ts
+++ b/types/clownface/index.d.ts
@@ -77,8 +77,8 @@ declare namespace clownface {
         namedNode(values: Array<string | NamedNode>): SafeClownface<D, NamedNode>;
 
         // tslint:disable:no-unnecessary-generics
-        in<X extends Term = Term>(predicates: SingleOrArrayOfTerms): SafeClownface<D, X>;
-        out<X extends Term = Term>(predicates: SingleOrArrayOfTerms): SafeClownface<D, X>;
+        in<X extends Term = Term>(predicates?: SingleOrArrayOfTerms): SafeClownface<D, X>;
+        out<X extends Term = Term>(predicates?: SingleOrArrayOfTerms): SafeClownface<D, X>;
 
         has<X extends Term = Term>(predicates: SingleOrArrayOfTerms, objects?: SingleOrArrayOfTermsOrLiterals): SafeClownface<D, X>;
 
diff --git a/types/clownface/lib/Clownface.d.ts b/types/clownface/lib/Clownface.d.ts
index 4079646b55..81cbb4b6c0 100644
--- a/types/clownface/lib/Clownface.d.ts
+++ b/types/clownface/lib/Clownface.d.ts
@@ -51,8 +51,8 @@ declare class Clownface<D extends DatasetCore = DatasetCore, T extends Term = Te
     namedNode(values: Array<string | NamedNode>): SafeClownface<D, NamedNode>;
 
     // tslint:disable:no-unnecessary-generics
-    in<X extends Term = Term>(predicates: SingleOrArrayOfTerms): SafeClownface<D, X>;
-    out<X extends Term = Term>(predicates: SingleOrArrayOfTerms): SafeClownface<D, X>;
+    in<X extends Term = Term>(predicates?: SingleOrArrayOfTerms): SafeClownface<D, X>;
+    out<X extends Term = Term>(predicates?: SingleOrArrayOfTerms): SafeClownface<D, X>;
 
     has<X extends Term = Term>(predicates: SingleOrArrayOfTerms, objects?: SingleOrArrayOfTermsOrLiterals): SafeClownface<D, X>;