diff --git a/internal/httpproxy/loop.go b/internal/httpproxy/loop.go
index d513d361..182958b7 100644
--- a/internal/httpproxy/loop.go
+++ b/internal/httpproxy/loop.go
@@ -13,6 +13,8 @@ import (
 	"github.com/qdm12/golibs/logging"
 )
 
+var _ Looper = (*Loop)(nil)
+
 type Looper interface {
 	Runner
 	loopstate.Getter
diff --git a/internal/loopstate/state.go b/internal/loopstate/state.go
index 2a8384bb..a19d413c 100644
--- a/internal/loopstate/state.go
+++ b/internal/loopstate/state.go
@@ -6,6 +6,8 @@ import (
 	"github.com/qdm12/gluetun/internal/models"
 )
 
+var _ Manager = (*State)(nil)
+
 type Manager interface {
 	Locker
 	Getter
diff --git a/internal/openvpn/loop.go b/internal/openvpn/loop.go
index 2271b788..dc9d7cbb 100644
--- a/internal/openvpn/loop.go
+++ b/internal/openvpn/loop.go
@@ -15,6 +15,8 @@ import (
 	"github.com/qdm12/golibs/logging"
 )
 
+var _ Looper = (*Loop)(nil)
+
 type Looper interface {
 	Runner
 	loopstate.Getter
diff --git a/internal/publicip/fetch.go b/internal/publicip/fetch.go
index 808476d7..7081018d 100644
--- a/internal/publicip/fetch.go
+++ b/internal/publicip/fetch.go
@@ -12,6 +12,8 @@ import (
 	"strings"
 )
 
+var _ Fetcher = (*Fetch)(nil)
+
 type Fetcher interface {
 	FetchPublicIP(ctx context.Context) (ip net.IP, err error)
 }