diff --git a/vlib/json/json_omitempty_types_test.v b/vlib/json/json_omitempty_types_test.v
new file mode 100644
index 0000000000..38050badc7
--- /dev/null
+++ b/vlib/json/json_omitempty_types_test.v
@@ -0,0 +1,104 @@
+import json
+
+struct OmitEmptyStruct {
+	bug Struct [omitempty]
+}
+
+type MyAlias = string
+
+struct OmitEmptyAlias {
+	bug MyAlias [omitempty]
+}
+
+struct Struct {
+	name string
+}
+
+struct OmitEmptyMap {
+	bug map[string]string [omitempty]
+}
+
+struct OmitEmptyArray {
+	bug []string [omitempty]
+}
+
+type MySum = int | string
+
+struct OmitEmptySumType {
+	bug MySum [omitempty]
+}
+
+fn main() {
+	test_struct()
+	test_alias()
+	test_map()
+	test_sumtype()
+	test_array()
+}
+
+fn test_struct() {
+	test2 := OmitEmptyStruct{
+		bug: Struct{}
+	}
+	encoded2 := json.encode(test2)
+	dump(encoded2)
+	test := OmitEmptyStruct{
+		bug: Struct{
+			name: 'mybug'
+		}
+	}
+	encoded := json.encode(test)
+	dump(encoded)
+}
+
+fn test_alias() {
+	test3 := OmitEmptyAlias{
+		bug: ''
+	}
+	encoded3 := json.encode(test3)
+	dump(encoded3)
+	test4 := OmitEmptyAlias{
+		bug: 'foo'
+	}
+	encoded4 := json.encode(test4)
+	dump(encoded4)
+}
+
+fn test_map() {
+	test3 := OmitEmptyMap{
+		bug: {}
+	}
+	encoded3 := json.encode(test3)
+	dump(encoded3)
+	test4 := OmitEmptyMap{
+		bug: {
+			'foo': 'bar'
+		}
+	}
+	encoded4 := json.encode(test4)
+	dump(encoded4)
+}
+
+fn test_sumtype() {
+	test3 := OmitEmptySumType{}
+	encoded3 := json.encode(test3)
+	dump(encoded3)
+	test4 := OmitEmptySumType{
+		bug: 1
+	}
+	encoded4 := json.encode(test4)
+	dump(encoded4)
+}
+
+fn test_array() {
+	test3 := OmitEmptyArray{
+		bug: []
+	}
+	encoded3 := json.encode(test3)
+	dump(encoded3)
+	test4 := OmitEmptyArray{
+		bug: ['1']
+	}
+	encoded4 := json.encode(test4)
+	dump(encoded4)
+}
diff --git a/vlib/v/gen/c/json.v b/vlib/v/gen/c/json.v
index db3ba06f37..b81537b48a 100644
--- a/vlib/v/gen/c/json.v
+++ b/vlib/v/gen/c/json.v
@@ -694,7 +694,22 @@ fn (mut g Gen) gen_struct_enc_dec(utyp ast.Type, type_info ast.TypeInfo, styp st
 			} else if field.typ == ast.string_type {
 				enc.writeln('${indent}if (${prefix_enc}${op}${c_name(field.name)}.len != 0)')
 			} else {
-				enc.writeln('${indent}if (${prefix_enc}${op}${c_name(field.name)} != ${g.type_default(field.typ)})')
+				if field_sym.kind in [.alias, .sum_type, .map, .array, .struct_] {
+					ptr_typ := g.equality_fn(field.typ)
+					if field_sym.kind == .alias {
+						enc.writeln('${indent}if (!${ptr_typ}_alias_eq(${prefix_enc}${op}${c_name(field.name)}, ${g.type_default(field.typ)}))')
+					} else if field_sym.kind == .sum_type {
+						enc.writeln('${indent}if (${prefix_enc}${op}${c_name(field.name)}._typ != 0)')
+					} else if field_sym.kind == .map {
+						enc.writeln('${indent}if (!${ptr_typ}_map_eq(${prefix_enc}${op}${c_name(field.name)}, ${g.type_default(field.typ)}))')
+					} else if field_sym.kind == .array {
+						enc.writeln('${indent}if (!${ptr_typ}_arr_eq(${prefix_enc}${op}${c_name(field.name)}, ${g.type_default(field.typ)}))')
+					} else if field_sym.kind == .struct_ {
+						enc.writeln('${indent}if (!${ptr_typ}_struct_eq(${prefix_enc}${op}${c_name(field.name)}, ${g.type_default(field.typ)}))')
+					}
+				} else {
+					enc.writeln('${indent}if (${prefix_enc}${op}${c_name(field.name)} != ${g.type_default(field.typ)})')
+				}
 			}
 		}
 		if !is_js_prim(field_type) {