diff --git a/src/shared/util.c b/src/shared/util.c
index e3d4a9457..1526b92c2 100644
--- a/src/shared/util.c
+++ b/src/shared/util.c
@@ -2539,7 +2539,7 @@ int getttyname_malloc(int fd, char **r) {
         assert(r);
 
         k = ttyname_r(fd, path, sizeof(path));
-        if (k != 0)
+        if (k > 0)
                 return -k;
 
         char_array_0(path);