diff --git a/libnetwork/iptables/firewalld.go b/libnetwork/iptables/firewalld.go
index e9fa0bf6b6..a09d78e7f5 100644
--- a/libnetwork/iptables/firewalld.go
+++ b/libnetwork/iptables/firewalld.go
@@ -268,16 +268,16 @@ func (fwd *firewalldConnection) setupDockerZone() error {
 	return nil
 }
 
-// AddInterfaceFirewalld adds the interface to the trusted zone. It is a
-// no-op if firewalld is not running.
-func AddInterfaceFirewalld(intf string) error {
-	if !firewalld.isRunning() {
+// addInterface adds the interface to the trusted zone. It is a no-op if
+// firewalld is not running or firewalldConnection not initialized.
+func (fwd *firewalldConnection) addInterface(intf string) error {
+	if !fwd.isRunning() {
 		return nil
 	}
 
 	var intfs []string
 	// Check if interface is already added to the zone
-	if err := firewalld.sysObj.Call(dbusInterface+".zone.getInterfaces", 0, dockerZone).Store(&intfs); err != nil {
+	if err := fwd.sysObj.Call(dbusInterface+".zone.getInterfaces", 0, dockerZone).Store(&intfs); err != nil {
 		return err
 	}
 	// Return if interface is already part of the zone
@@ -288,16 +288,16 @@ func AddInterfaceFirewalld(intf string) error {
 
 	log.G(context.TODO()).Debugf("Firewalld: adding %s interface to %s zone", intf, dockerZone)
 	// Runtime
-	if err := firewalld.sysObj.Call(dbusInterface+".zone.addInterface", 0, dockerZone, intf).Err; err != nil {
+	if err := fwd.sysObj.Call(dbusInterface+".zone.addInterface", 0, dockerZone, intf).Err; err != nil {
 		return err
 	}
 	return nil
 }
 
-// DelInterfaceFirewalld removes the interface from the trusted zone It is a
-// no-op if firewalld is not running.
-func DelInterfaceFirewalld(intf string) error {
-	if !firewalld.isRunning() {
+// delInterface removes the interface from the trusted zone It is a no-op if
+// firewalld is not running or firewalldConnection not initialized.
+func (fwd *firewalldConnection) delInterface(intf string) error {
+	if !fwd.isRunning() {
 		return nil
 	}
 
@@ -319,6 +319,18 @@ func DelInterfaceFirewalld(intf string) error {
 	return nil
 }
 
+// AddInterfaceFirewalld adds the interface to the trusted zone. It is a
+// no-op if firewalld is not running.
+func AddInterfaceFirewalld(intf string) error {
+	return firewalld.addInterface(intf)
+}
+
+// DelInterfaceFirewalld removes the interface from the trusted zone It is a
+// no-op if firewalld is not running.
+func DelInterfaceFirewalld(intf string) error {
+	return firewalld.delInterface(intf)
+}
+
 type interfaceNotFound struct{ error }
 
 func (interfaceNotFound) NotFound() {}
diff --git a/libnetwork/iptables/firewalld_test.go b/libnetwork/iptables/firewalld_test.go
index d715d19f81..62490153a0 100644
--- a/libnetwork/iptables/firewalld_test.go
+++ b/libnetwork/iptables/firewalld_test.go
@@ -112,4 +112,12 @@ func TestFirewalldUninitialized(t *testing.T) {
 	if fwd.isRunning() {
 		t.Error("did not expect an uninitialized firewalldConnection to be running")
 	}
+	err := fwd.addInterface("anything")
+	if err != nil {
+		t.Errorf("unexpected error when calling addInterface on an uninitialized firewalldConnection: %v", err)
+	}
+	err = fwd.delInterface("anything")
+	if err != nil {
+		t.Errorf("unexpected error when calling delInterface on an uninitialized firewalldConnection: %v", err)
+	}
 }
diff --git a/libnetwork/iptables/iptables.go b/libnetwork/iptables/iptables.go
index 4483a2cf38..7a5cfcf1f1 100644
--- a/libnetwork/iptables/iptables.go
+++ b/libnetwork/iptables/iptables.go
@@ -206,11 +206,11 @@ func (iptable IPTable) ProgramChain(c *ChainInfo, bridgeName string, hairpinMode
 
 	// Either add or remove the interface from the firewalld zone, if firewalld is running.
 	if enable {
-		if err := AddInterfaceFirewalld(bridgeName); err != nil {
+		if err := firewalld.addInterface(bridgeName); err != nil {
 			return err
 		}
 	} else {
-		if err := DelInterfaceFirewalld(bridgeName); err != nil && !errdefs.IsNotFound(err) {
+		if err := firewalld.delInterface(bridgeName); err != nil && !errdefs.IsNotFound(err) {
 			return err
 		}
 	}