diff --git a/index.d.ts b/index.d.ts
index fca580a4a..c78972fdf 100644
--- a/index.d.ts
+++ b/index.d.ts
@@ -29,6 +29,9 @@ export type SnapshotOptions = {
 };
 
 export interface Assertions {
+	/** Assert that `actual` is [truthy](https://developer.mozilla.org/en-US/docs/Glossary/Truthy). Comes with power-assert. */
+	assert: AssertAssertion;
+
 	/** Assert that `actual` is [deeply equal](https://github.com/concordancejs/concordance#comparison-details) to `expected`. */
 	deepEqual: DeepEqualAssertion;
 
@@ -96,6 +99,14 @@ export interface Assertions {
 	truthy: TruthyAssertion;
 }
 
+export interface AssertAssertion {
+	/** Assert that `actual` is [truthy](https://developer.mozilla.org/en-US/docs/Glossary/Truthy). Comes with power-assert. */
+	(actual: any, message?: string): void;
+
+	/** Skip this assertion. */
+	skip(actual: any, message?: string): void;
+}
+
 export interface DeepEqualAssertion {
 	/** Assert that `actual` is [deeply equal](https://github.com/concordancejs/concordance#comparison-details) to `expected`. */
 	<ValueType = any>(actual: ValueType, expected: ValueType, message?: string): void;
diff --git a/index.js.flow b/index.js.flow
index 2277fffba..cc31f065f 100644
--- a/index.js.flow
+++ b/index.js.flow
@@ -42,6 +42,9 @@ export type SnapshotOptions = {
 };
 
 export interface Assertions {
+	/** Assert that `actual` is [truthy](https://developer.mozilla.org/en-US/docs/Glossary/Truthy). Comes with power-assert. */
+	assert: AssertAssertion;
+
 	/** Assert that `actual` is [deeply equal](https://github.com/concordancejs/concordance#comparison-details) to `expected`. */
 	deepEqual: DeepEqualAssertion;
 
@@ -109,6 +112,14 @@ export interface Assertions {
 	truthy: TruthyAssertion;
 }
 
+export interface AssertAssertion {
+	/** Assert that `actual` is [truthy](https://developer.mozilla.org/en-US/docs/Glossary/Truthy). Comes with power-assert. */
+	(actual: any, message?: string): void;
+
+	/** Skip this assertion. */
+	skip(actual: any, message?: string): void;
+}
+
 export interface DeepEqualAssertion {
 	/** Assert that `actual` is [deeply equal](https://github.com/concordancejs/concordance#comparison-details) to `expected`. */
 	(actual: any, expected: any, message?: string): void;