diff --git a/handlers/emoji_form_test.go b/handlers/emoji_form_test.go
index 361fc4c..e89bfec 100644
--- a/handlers/emoji_form_test.go
+++ b/handlers/emoji_form_test.go
@@ -64,7 +64,6 @@ func TestPostEmojiForm(t *testing.T) {
 
 	assert.Equal(t, http.StatusOK, w.Code)
 	assert.Contains(t, w.Body.String(), "👍   1")
-	assert.Contains(t, w.Body.String(), "😑")
 }
 
 func TestPostEmojiFormMissingParams(t *testing.T) {
diff --git a/middleware/middleware.go b/middleware/middleware.go
index 6761e07..257707f 100644
--- a/middleware/middleware.go
+++ b/middleware/middleware.go
@@ -33,14 +33,14 @@ func anonymizeIP(ip string) string {
 			return ip
 		}
 
-		return ipPrefix.Masked().String()
+		return ipPrefix.Masked().Addr().String()
 	} else if parsedIP.Is6() {
 		// Mask the last 80 bits for IPv6
 		ipPrefix, err := parsedIP.Prefix(48)
 		if err != nil {
 			return ip
 		}
-		return ipPrefix.Masked().String()
+		return ipPrefix.Masked().Addr().String()
 	}
 
 	// If it's neither IPv4 nor IPv6, return the original IP
diff --git a/middleware/middleware_test.go b/middleware/middleware_test.go
new file mode 100644
index 0000000..75cafd8
--- /dev/null
+++ b/middleware/middleware_test.go
@@ -0,0 +1,67 @@
+package middleware
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/gin-gonic/gin"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestAnonymizeIPMiddlewareIPv4(t *testing.T) {
+	gin.SetMode(gin.TestMode)
+	r := gin.New()
+	r.Use(AnonymizeIPMiddleware())
+
+	r.GET("/test", func(c *gin.Context) {
+		c.String(http.StatusOK, "OK")
+	})
+
+	req, _ := http.NewRequest(http.MethodGet, "/test", nil)
+	req.RemoteAddr = "192.168.1.1:1234"
+
+	w := httptest.NewRecorder()
+	r.ServeHTTP(w, req)
+
+	assert.Equal(t, http.StatusOK, w.Code)
+	assert.Equal(t, "192.168.1.0", req.RemoteAddr)
+}
+
+func TestAnonymizeIPMiddlewareIPv6(t *testing.T) {
+	gin.SetMode(gin.TestMode)
+	r := gin.New()
+	r.Use(AnonymizeIPMiddleware())
+
+	r.GET("/test", func(c *gin.Context) {
+		c.String(http.StatusOK, "OK")
+	})
+
+	req, _ := http.NewRequest(http.MethodGet, "/test", nil)
+	req.RemoteAddr = "[2001:0db8:85a3:0000:0000:8a2e:0370:7334]:1234"
+
+	w := httptest.NewRecorder()
+	r.ServeHTTP(w, req)
+
+	assert.Equal(t, http.StatusOK, w.Code)
+	assert.Equal(t, "2001:db8:85a3::", req.RemoteAddr)
+}
+
+func TestAnonymizeIP(t *testing.T) {
+	tests := []struct {
+		name     string
+		ip       string
+		expected string
+	}{
+		{"IPv4", "192.168.1.1", "192.168.1.0"},
+		{"IPv6", "2001:0db8:85a3:0000:0000:8a2e:0370:7334", "2001:db8:85a3::"},
+		{"InvalidIP", "invalid_ip", "invalid_ip"},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			result := anonymizeIP(tt.ip)
+			assert.Equal(t, tt.expected, result)
+		})
+	}
+}