diff --git a/demo/demo.sol b/demo/demo.sol
index d3a7d81..665f3c9 100644
--- a/demo/demo.sol
+++ b/demo/demo.sol
@@ -86,6 +86,11 @@ contract DemoTest is DSTest {
         emit log("\n");
         assertTrue(false, err);
 
+        emit log("## assertFalse(bool)\n");
+        assertFalse(true);
+        emit log("\n");
+        assertFalse(true, err);
+
         emit log("\n## assertEq(address,address)\n");
         assertEq(address(this), msg.sender);
         emit log("\n");
diff --git a/src/test.sol b/src/test.sol
index 96d3c15..5ea9830 100644
--- a/src/test.sol
+++ b/src/test.sol
@@ -69,6 +69,19 @@ contract DSTest {
         }
     }
 
+    function assertFalse(bool condition) internal {
+        if (condition) {
+            emit log("Error: Assertion Failed");
+            fail();
+        }
+    }
+    function assertFalse(bool condition, string memory err) internal {
+        if (condition) {
+            emit log_named_string("Error", err);
+            assertFalse(condition);
+        }
+    }
+
     function assertEq(address a, address b) internal {
         if (a != b) {
             emit log("Error: a == b not satisfied [address]");