diff --git a/libs/libc/stdio/lib_dtoa_engine.c b/libs/libc/stdio/lib_dtoa_engine.c
index 51e9b3902c..4bc8884f91 100644
--- a/libs/libc/stdio/lib_dtoa_engine.c
+++ b/libs/libc/stdio/lib_dtoa_engine.c
@@ -69,7 +69,7 @@ int __dtoa_engine(double x, FAR struct dtoa_s *dtoa, int max_digits,
   uint8_t flags = 0;
   int i;
 
-  if (__builtin_signbit(x))
+  if (x < 0)
     {
       flags |= DTOA_MINUS;
       x = -x;