diff --git a/criu/filesystems.c b/criu/filesystems.c
index d52fe5c3a..e640096d8 100644
--- a/criu/filesystems.c
+++ b/criu/filesystems.c
@@ -213,7 +213,7 @@ static int write_binfmt_misc_entry(char *mp, char *buf, BinfmtMiscEntry *bme)
 		snprintf(path, PATH_MAX, "%s/%s", mp, bme->name);
 
 		fd = open(path, O_WRONLY);
-		if (!fd) {
+		if (fd < 0) {
 			pr_perror("binfmt_misc: can't open %s", path);
 			goto out;
 		}
diff --git a/criu/sk-packet.c b/criu/sk-packet.c
index 6e0ad2d43..bcd4ff33e 100644
--- a/criu/sk-packet.c
+++ b/criu/sk-packet.c
@@ -325,7 +325,7 @@ static int open_socket_map(int pid, struct vma_area *vm)
 			 */
 
 			fd = dup(le->fe->fd);
-			if (!fd) {
+			if (fd < 0) {
 				pr_perror("Can't dup packet sk");
 				return -1;
 			}
diff --git a/test/zdtm/static/binfmt_misc.c b/test/zdtm/static/binfmt_misc.c
index 62b9b51e3..26f8b8192 100644
--- a/test/zdtm/static/binfmt_misc.c
+++ b/test/zdtm/static/binfmt_misc.c
@@ -120,7 +120,7 @@ int main(int argc, char **argv)
 	/* Register binfmt_entries */
 	sprintf(path, "%s/" "register", dirname);
 	fd = open(path, O_WRONLY);
-	if (!fd) {
+	if (fd < 0) {
 		fail("open");
 		exit(1);
 	}
@@ -145,7 +145,7 @@ int main(int argc, char **argv)
 	/* Disable one of the entries */
 	sprintf(path, "%s/%s", dirname, NAME[0]);
 	fd = open(path, O_WRONLY);
-	if (!fd || write(fd, "0", 1) != 1) {
+	if (fd < 0 || write(fd, "0", 1) != 1) {
 		fail("Can't disable %s\n", path);
 		exit(1);
 	}