1 files changed, 4 insertions, 0 deletions
diff --git a/math/s_cacosh.c b/math/s_cacosh.c
index e921f0763e..ada7ca5af6 100644
--- a/math/s_cacosh.c
+++ b/math/s_cacosh.c
@@ -80,6 +80,10 @@ __cacosh (__complex__ double x)
       __imag__ y += __imag__ x;
 
       res = __clog (y);
+
+      /* We have to use the positive branch.  */
+      if (__real__ res < 0.0)
+	res = -res;
     }
 
   return res;