diff --git a/src/c/printer/float_to_string.d b/src/c/printer/float_to_string.d
index 29ee56d8e..d2d06979d 100644
--- a/src/c/printer/float_to_string.d
+++ b/src/c/printer/float_to_string.d
@@ -105,7 +105,7 @@ si_float_to_string_free(cl_object buffer_or_nil, cl_object number,
         buffer = VALUES(1);
         e = fix(exp);
 
-        if (ecl_minusp(number)) {
+        if (ecl_signbit(number)) {
                 insert_char(buffer, base++, '-');
         }
         /* Do we have to print in exponent notation? */