diff --git a/vlib/encoding/binary/serialize.v b/vlib/encoding/binary/serialize.v
index 33e02d963c..328da6ff30 100644
--- a/vlib/encoding/binary/serialize.v
+++ b/vlib/encoding/binary/serialize.v
@@ -127,7 +127,7 @@ fn encode_primitive[T](mut s EncodeState, value T) ! {
 		s.put_u64(u64(value))
 	} $else {
 		// TODO: `any` type support?
-		return error('${@FN}unsupported type ${typeof(value).name}')
+		return error('${@FN}(): unsupported type ${typeof(value).name}')
 	}
 }
 
@@ -309,15 +309,15 @@ fn decode_primitive[T](mut s DecodeState, value T) !T {
 		return T(s.get_u64()!)
 	} $else {
 		// TODO: `any` type support?
-		return error('${@FN}unsupported type ${typeof(value).name}')
+		return error('${@FN}(): unsupported type ${typeof(value).name}')
 	}
-	return error('impossiable error')
+	return error('${@FN}(): impossible error')
 }
 
 fn decode_array[T](mut s DecodeState, _ []T) ![]T {
 	len := int(s.get_u64()!)
 	if len <= 0 || s.offset + len > s.b.len {
-		return error('invalid array length decode from stream')
+		return error('${@FN}(): invalid array length decode from stream')
 	}
 	mut arr := []T{cap: len}
 	$if T is u8 {
@@ -327,7 +327,7 @@ fn decode_array[T](mut s DecodeState, _ []T) ![]T {
 	} $else {
 		for _ in 0 .. len {
 			if s.offset >= s.b.len {
-				return error('unexpected end of data')
+				return error('${@FN}(): unexpected end of data')
 			}
 			$if T is $array {
 				arr << decode_array(mut s, T{})!
@@ -348,7 +348,7 @@ fn decode_array[T](mut s DecodeState, _ []T) ![]T {
 fn decode_string(mut s DecodeState) !string {
 	len := int(s.get_u64()!)
 	if len <= 0 || s.offset + len > s.b.len {
-		return error('invalid string length decode from stream')
+		return error('${@FN}(): invalid string length decode from stream')
 	}
 	str := unsafe { s.b[s.offset..s.offset + len].bytestr() }
 	s.offset += len
@@ -379,7 +379,7 @@ type Any = int
 fn decode_map[K, V](mut s DecodeState, _ map[K]V) !map[K]V {
 	len := int(s.get_u64()!)
 	if len <= 0 || s.offset + len > s.b.len {
-		return error('invalid map length decode from stream')
+		return error('${@FN}(): invalid map length decode from stream')
 	}
 
 	mut m := map[K]V{}
@@ -395,17 +395,19 @@ fn decode_map[K, V](mut s DecodeState, _ map[K]V) !map[K]V {
 		}
 
 		// decode value
-		mut v := Any(0)
-		$if V is $string {
-			v = decode_string(mut s)!
-		} $else $if V is $struct {
-			v = decode_struct(mut s, V{})!
+		$if V is $struct {
+			v := decode_struct(mut s, V{})!
+			m[k as K] = v
 		} $else $if V is $map {
-			v = decode_map(mut s, V{})!
+			v := decode_map(mut s, V{})!
+			m[k as K] = v
+		} $else $if V is $string {
+			v := decode_string(mut s)!
+			m[k as K] = v
 		} $else {
-			v = decode_primitive(mut s, unsafe { V(0) })!
+			v := decode_primitive(mut s, unsafe { V(0) })!
+			m[k as K] = v
 		}
-		m[k as K] = v as V
 	}
 	return m
 }
@@ -413,7 +415,7 @@ fn decode_map[K, V](mut s DecodeState, _ map[K]V) !map[K]V {
 @[inline]
 fn (mut s DecodeState) get_u64() !u64 {
 	if s.offset + 8 > s.b.len {
-		return error('bytes length is not enough for u64')
+		return error('${@FN}(): bytes length is not enough for u64')
 	}
 	defer {
 		s.offset += 8
@@ -428,7 +430,7 @@ fn (mut s DecodeState) get_u64() !u64 {
 @[inline]
 fn (mut s DecodeState) get_u32() !u32 {
 	if s.offset + 4 > s.b.len {
-		return error('bytes length is not enough for u32')
+		return error('${@FN}(): bytes length is not enough for u32')
 	}
 	defer {
 		s.offset += 4
@@ -443,7 +445,7 @@ fn (mut s DecodeState) get_u32() !u32 {
 @[inline]
 fn (mut s DecodeState) get_u16() !u16 {
 	if s.offset + 2 > s.b.len {
-		return error('bytes length is not enough for u16')
+		return error('${@FN}(): bytes length is not enough for u16')
 	}
 	defer {
 		s.offset += 2
@@ -458,7 +460,7 @@ fn (mut s DecodeState) get_u16() !u16 {
 @[inline]
 fn (mut s DecodeState) get_u8() !u8 {
 	if s.offset + 1 > s.b.len {
-		return error('bytes length is not enough for u8')
+		return error('${@FN}(): bytes length is not enough for u8')
 	}
 	defer {
 		s.offset += 1
diff --git a/vlib/encoding/binary/serialize_test.v b/vlib/encoding/binary/serialize_test.v
index 48460a1245..4fb3111c79 100644
--- a/vlib/encoding/binary/serialize_test.v
+++ b/vlib/encoding/binary/serialize_test.v
@@ -192,6 +192,10 @@ fn test_encode_decode_array() {
 	}
 }
 
+struct St {
+	i int
+}
+
 fn test_encode_decode_map() {
 	a_map_string_string := {
 		'abc': 'def'
@@ -242,6 +246,10 @@ fn test_encode_decode_map() {
 		'abc': usize(432211)
 	}
 
+	a_map_string_struct := {
+		's': St{1}
+	}
+
 	b_map_string_string := encode_binary(a_map_string_string)!
 	b_map_string_int := encode_binary(a_map_string_int)!
 	b_map_string_u8 := encode_binary(a_map_string_u8)!
@@ -258,6 +266,7 @@ fn test_encode_decode_map() {
 	b_map_string_rune := encode_binary(a_map_string_rune)!
 	b_map_string_isize := encode_binary(a_map_string_isize)!
 	b_map_string_usize := encode_binary(a_map_string_usize)!
+	b_map_string_struct := encode_binary(a_map_string_struct)!
 
 	c_map_string_string := decode_binary[map[string]string](b_map_string_string)!
 	c_map_string_int := decode_binary[map[string]int](b_map_string_int)!
@@ -275,6 +284,7 @@ fn test_encode_decode_map() {
 	c_map_string_rune := decode_binary[map[string]rune](b_map_string_rune)!
 	c_map_string_isize := decode_binary[map[string]isize](b_map_string_isize)!
 	c_map_string_usize := decode_binary[map[string]usize](b_map_string_usize)!
+	c_map_string_struct := decode_binary[map[string]St](b_map_string_struct)!
 
 	assert a_map_string_string == c_map_string_string
 	assert a_map_string_int == c_map_string_int
@@ -291,6 +301,7 @@ fn test_encode_decode_map() {
 	assert a_map_string_rune == c_map_string_rune
 	assert a_map_string_isize == c_map_string_isize
 	assert a_map_string_usize == c_map_string_usize
+	assert a_map_string_struct == c_map_string_struct
 
 	assert b_map_string_string == [u8(1), 0, 0, 0, 0, 0, 0, 0, 3, 0, 0, 0, 0, 0, 0, 0, 97, 98,
 		99, 3, 0, 0, 0, 0, 0, 0, 0, 100, 101, 102]
@@ -331,6 +342,8 @@ fn test_encode_decode_map() {
 		assert b_map_string_usize == [u8(1), 0, 0, 0, 0, 0, 0, 0, 3, 0, 0, 0, 0, 0, 0, 0, 97, 98,
 			99, 83, 152, 6, 0]
 	}
+	assert b_map_string_struct == [u8(1), 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 115, 1,
+		0, 0, 0, 0, 0, 0, 0]
 }
 
 struct MyStruct {