diff --git a/decons.lisp b/decons.lisp
index 60a1d48..58c2409 100644
--- a/decons.lisp
+++ b/decons.lisp
@@ -37,4 +37,4 @@
 ;;;; parameterized functions
 
 (defun line (x)
-  #'(lambda (w b) (+ b (* w x))))
+  #'(lambda (theta) (+ (cadr theta) (* (car theta) x))))
diff --git a/test-decons.lisp b/test-decons.lisp
index e7c89a6..89cfaee 100644
--- a/test-decons.lisp
+++ b/test-decons.lisp
@@ -11,7 +11,24 @@
 (defun run ()
   (let ((t:*test-suite* (t:test-suite "decons")))
     (test-basic)
+    (test-line)
     (t:show-result)))
 
 (deftest test-basic ()
-  (== decons:*pi* 3.14159))
+  (== decons:*pi* 3.14159)
+  (let ((c (make-instance 'decons:circle :radius 2.0)))
+    (== (decons:area c) 12.56636))
+  (== (funcall (decons:double #'1+) 7) 16)
+  (== (decons:absv 7) 7)
+  (== (decons:absv -7) 7)
+  (== (decons:remainder 7 4) 3)
+)
+
+(deftest test-line ()
+  (let ((p1 (decons:line 0.0))
+        (p2 (decons:line 1.0))
+        (ds1 '((2.0 1.0 4.0 3.0)
+               (1.8 1.2 4.2 3.3))))
+    (== (funcall p1 '(0.5 2.0)) 2.0)
+    (== (funcall p2 '(0.5 2.0)) 2.5)
+))