diff --git a/query/encode.go b/query/encode.go
index ffb2097..ffe56bc 100644
--- a/query/encode.go
+++ b/query/encode.go
@@ -282,7 +282,7 @@ func reflectValue(values url.Values, val reflect.Value, scope string) error {
 
 // valueString returns the string representation of a value.
 func valueString(v reflect.Value, opts tagOptions, sf reflect.StructField) string {
-	for v.Kind() == reflect.Ptr {
+	for v.Kind() == reflect.Ptr || (v.Kind() == reflect.Interface && !v.IsNil()) {
 		if v.IsNil() {
 			return ""
 		}
diff --git a/query/encode_test.go b/query/encode_test.go
index 241e4f1..82b05bd 100644
--- a/query/encode_test.go
+++ b/query/encode_test.go
@@ -265,6 +265,18 @@ func TestValues_Slices(t *testing.T) {
 			}{[]bool{true, false}},
 			url.Values{"V": {"1 0"}},
 		},
+		{
+			struct {
+				V []interface{} `url:",space,int"`
+			}{[]interface{}{true, false}},
+			url.Values{"V": {"1 0"}},
+		},
+		{
+			struct {
+				V []interface{} `layout:"2006-01-02"`
+			}{[]interface{}{time.Date(2026, 10, 18, 0, 0, 0, 0, time.UTC)}},
+			url.Values{"V": {"2026-10-18"}},
+		},
 	}
 
 	for _, tt := range tests {