diff --git a/src/libsystemd-network/sd-dhcp-server.c b/src/libsystemd-network/sd-dhcp-server.c
index a0af256dee..faeab0fd30 100644
--- a/src/libsystemd-network/sd-dhcp-server.c
+++ b/src/libsystemd-network/sd-dhcp-server.c
@@ -67,7 +67,7 @@ int sd_dhcp_server_set_address(sd_dhcp_server *server, struct in_addr *address,
 }
 
 bool sd_dhcp_server_is_running(sd_dhcp_server *server) {
-        assert_return(server, -EINVAL);
+        assert_return(server, false);
 
         return !!server->receive_message;
 }
diff --git a/src/libsystemd-network/sd-ipv4ll.c b/src/libsystemd-network/sd-ipv4ll.c
index 0cb77ccf71..f080c5c0a7 100644
--- a/src/libsystemd-network/sd-ipv4ll.c
+++ b/src/libsystemd-network/sd-ipv4ll.c
@@ -507,7 +507,7 @@ error:
 }
 
 bool sd_ipv4ll_is_running(sd_ipv4ll *ll) {
-        assert_return(ll, -EINVAL);
+        assert_return(ll, false);
 
         return !IN_SET(ll->state, IPV4LL_STATE_INIT, IPV4LL_STATE_STOPPED);
 }
diff --git a/src/udev/cdrom_id/cdrom_id.c b/src/udev/cdrom_id/cdrom_id.c
index 3d74ae50f1..775da0355d 100644
--- a/src/udev/cdrom_id/cdrom_id.c
+++ b/src/udev/cdrom_id/cdrom_id.c
@@ -106,11 +106,11 @@ static bool is_mounted(const char *device)
         bool mounted = false;
 
         if (stat(device, &statbuf) < 0)
-                return -ENODEV;
+                return false;
 
         fp = fopen("/proc/self/mountinfo", "re");
         if (fp == NULL)
-                return -ENOSYS;
+                return false;
         while (fscanf(fp, "%*s %*s %i:%i %*[^\n]", &maj, &min) == 2) {
                 if (makedev(maj, min) == statbuf.st_rdev) {
                         mounted = true;