diff --git a/t/unless.t b/t/unless.t
index 524eefb..c931dd9 100644
--- a/t/unless.t
+++ b/t/unless.t
@@ -3,3 +3,7 @@
 
 (expect "unless - false condition"
         (equal 'ok (unless nil 'ok)))
+
+(let ((a 'ok))
+  (unless t (set a 'fail))
+  (expect "unless - does not evaluate on true" (equal a 'ok)))
diff --git a/t/when.t b/t/when.t
index 11a3c29..0a24226 100644
--- a/t/when.t
+++ b/t/when.t
@@ -3,3 +3,7 @@
 
 (expect "when - false condition"
         (null (when nil 'fail)))
+
+(let ((a 'ok))
+  (when nil (set a 'fail))
+  (expect "when - does not evaluate on false" (equal a 'ok)))