diff --git a/lisp/calc/calc-cplx.el b/lisp/calc/calc-cplx.el
index 4a453a73d72..35cd31dfb4f 100644
--- a/lisp/calc/calc-cplx.el
+++ b/lisp/calc/calc-cplx.el
@@ -273,8 +273,8 @@
     (or (eq (car-safe val) 'special-const)
 	(equal val '(cplx 0 1))
 	(and (eq (car-safe val) 'polar)
-	     (eq (nth 1 val) 0)
-	     (Math-equal (nth 1 val) (math-quarter-circle nil))))))
+	     (eq (nth 1 val) 1)
+	     (Math-equal (nth 2 val) (math-quarter-circle nil))))))
 
 ;;; Extract the real or complex part of a complex number.  [R N] [Public]
 ;;; Also extracts the real part of a modulo form.