diff --git a/src/detail/io/WktWriter.cpp b/src/detail/io/WktWriter.cpp
index 3b8ba401..dba3369d 100644
--- a/src/detail/io/WktWriter.cpp
+++ b/src/detail/io/WktWriter.cpp
@@ -28,7 +28,10 @@ namespace impl {
 auto
 writeFT(std::ostream &s, const CGAL::Gmpq &ft) -> std::ostream &
 {
-  s << ft;
+  if (ft == -0.0)
+    s << 0;
+  else
+    s << ft;
   return s;
 }