diff --git a/src/basic/exec-util.c b/src/basic/exec-util.c
index 32c6418482..a6c020b0f8 100644
--- a/src/basic/exec-util.c
+++ b/src/basic/exec-util.c
@@ -102,7 +102,7 @@ static int do_execute(
                 alarm(DIV_ROUND_UP(timeout, USEC_PER_SEC));
 
         STRV_FOREACH(e, envp)
-                if (putenv(*e) < 0)
+                if (putenv(*e) != 0)
                         return log_error_errno(errno, "Failed to set environment variable: %m");
 
         STRV_FOREACH(path, paths) {