diff --git a/vlib/builtin/array_d_gcboehm_opt.v b/vlib/builtin/array_d_gcboehm_opt.v
index 27f92cde69..d40ed47897 100644
--- a/vlib/builtin/array_d_gcboehm_opt.v
+++ b/vlib/builtin/array_d_gcboehm_opt.v
@@ -105,9 +105,9 @@ fn (a array) repeat_to_depth_noscan(count int, depth int) array {
 		for i in 0 .. count {
 			if depth > 0 {
 				ary_clone := unsafe { a.clone_to_depth_noscan(depth) }
-				unsafe { vmemcpy(arr.get_unsafe(i * a.len), &byte(ary_clone.data), a.len * a.element_size) }
+				unsafe { vmemcpy(arr.get_unsafe(i * a.len), &u8(ary_clone.data), a.len * a.element_size) }
 			} else {
-				unsafe { vmemcpy(arr.get_unsafe(i * a.len), &byte(a.data), a.len * a.element_size) }
+				unsafe { vmemcpy(arr.get_unsafe(i * a.len), &u8(a.data), a.len * a.element_size) }
 			}
 		}
 	}
@@ -167,7 +167,7 @@ fn (mut a array) pop_noscan() voidptr {
 		}
 	}
 	new_len := a.len - 1
-	last_elem := unsafe { &byte(a.data) + new_len * a.element_size }
+	last_elem := unsafe { &u8(a.data) + new_len * a.element_size }
 	a.len = new_len
 	// Note: a.cap is not changed here *on purpose*, so that
 	// further << ops on that array will be more efficient.
@@ -205,7 +205,7 @@ fn (a &array) clone_to_depth_noscan(depth int) array {
 		return arr
 	} else {
 		if !isnil(a.data) {
-			unsafe { vmemcpy(&byte(arr.data), a.data, a.cap * a.element_size) }
+			unsafe { vmemcpy(&u8(arr.data), a.data, a.cap * a.element_size) }
 		}
 		return arr
 	}
@@ -213,7 +213,7 @@ fn (a &array) clone_to_depth_noscan(depth int) array {
 
 fn (mut a array) push_noscan(val voidptr) {
 	a.ensure_cap_noscan(a.len + 1)
-	unsafe { vmemcpy(&byte(a.data) + a.element_size * a.len, val, a.element_size) }
+	unsafe { vmemcpy(&u8(a.data) + a.element_size * a.len, val, a.element_size) }
 	a.len++
 }
 
diff --git a/vlib/strings/builder.js.v b/vlib/strings/builder.js.v
index 4df19c2e82..22909bb782 100644
--- a/vlib/strings/builder.js.v
+++ b/vlib/strings/builder.js.v
@@ -12,22 +12,22 @@ pub mut:
 	initial_size int = 1
 }*/
 
-pub type Builder = []byte
+pub type Builder = []u8
 
 pub fn new_builder(initial_size int) Builder {
-	return []byte{cap: initial_size}
+	return []u8{cap: initial_size}
 }
 
 [deprecated: 'Use write_byte() instead']
-pub fn (mut b Builder) write_b(data byte) {
+pub fn (mut b Builder) write_b(data u8) {
 	b << data
 }
 
-pub fn (mut b Builder) write_byte(data byte) {
+pub fn (mut b Builder) write_byte(data u8) {
 	b << data
 }
 
-pub fn (mut b Builder) write(data []byte) ?int {
+pub fn (mut b Builder) write(data []u8) ?int {
 	if data.len == 0 {
 		return 0
 	}
@@ -35,7 +35,7 @@ pub fn (mut b Builder) write(data []byte) ?int {
 	return data.len
 }
 
-pub fn (b &Builder) byte_at(n int) byte {
+pub fn (b &Builder) byte_at(n int) u8 {
 	unsafe {
 		return b[n]
 	}