See the ticket for explanations.
diff --git a/library.scm b/library.scm
index 6a089955..02b5af36 100644
--- a/library.scm
+++ b/library.scm
@@ -1737,7 +1737,6 @@ EOF
(set! scheme#imag-part
(lambda (x)
(cond ((cplxnum? x) (%cplxnum-imag x))
- ((##core#inline "C_i_flonump" x) 0.0)
((number? x) 0)
(else (##sys#error-bad-number x 'imag-part)) )))