diff --git a/ansi-tests/atan.lsp b/ansi-tests/atan.lsp
index bb9d2a12e91856deb0b0d20f18cd29ecdb32ccc7..040c13aadec4d31e4d0d8dd5ea89b9331362a1f1 100644
--- a/ansi-tests/atan.lsp
+++ b/ansi-tests/atan.lsp
@@ -21,21 +21,23 @@
 (deftest atan.3
   (loop for type in '(short-float single-float double-float long-float)
 	for zero = (coerce 0 type)
-	unless (eql (atan zero 0) zero)
+	unless (eql (atan zero 1) zero)
 	collect type)
   nil)
 
 (deftest atan.4
   (loop for type in '(short-float single-float double-float long-float)
 	for zero = (coerce 0 type)
-	unless (eql (atan 0 zero) zero)
+	for one = (coerce 1 type)
+	unless (eql (atan 0 one) zero)
 	collect type)
   nil)
 
 (deftest atan.5
   (loop for type in '(short-float single-float double-float long-float)
 	for zero = (coerce 0 type)
-	unless (eql (atan zero zero) zero)
+	for one = (coerce 1 type)
+	unless (eql (atan zero one) zero)
 	collect type)
   nil)