diff --git a/bignum.c b/bignum.c
index 266cd933..93a765f5 100644
--- a/bignum.c
+++ b/bignum.c
@@ -1110,7 +1110,7 @@ sexp sexp_complex_sqrt (sexp ctx, sexp z) {
   r = sqrt(x*x + y*y);
   res = sexp_make_complex(ctx, SEXP_ZERO, SEXP_ZERO);
   sexp_complex_real(res) = sexp_make_flonum(ctx, sqrt((x+r)/2));
-  sexp_complex_imag(res) = sexp_make_flonum(ctx, ((y<0||(y==0&&1/y<0))?-1:1)*sqrt((-x+r)/2));
+  sexp_complex_imag(res) = sexp_make_flonum(ctx, ((y<-0.0)?-1:1)*sqrt((-x+r)/2));
   sexp_gc_release1(ctx);
   return res;
 }
diff --git a/tests/r7rs-tests.scm b/tests/r7rs-tests.scm
index 01772232..f07e1c10 100644
--- a/tests/r7rs-tests.scm
+++ b/tests/r7rs-tests.scm
@@ -994,6 +994,7 @@
 (test 3.0 (inexact (sqrt 9)))
 (test 1.4142135623731 (sqrt 2))
 (test 0.0+1.0i (inexact (sqrt -1)))
+(test 0.0+1.0i (sqrt -1.0-0.0i))
 
 (test '(2 0) (call-with-values (lambda () (exact-integer-sqrt 4)) list))
 (test '(2 1) (call-with-values (lambda () (exact-integer-sqrt 5)) list))