diff --git a/vlib/v/gen/native/amd64.v b/vlib/v/gen/native/amd64.v
index 89f7dbce96..fd611d541a 100644
--- a/vlib/v/gen/native/amd64.v
+++ b/vlib/v/gen/native/amd64.v
@@ -400,26 +400,51 @@ fn (mut c Amd64) inc_var(var Var, config VarConfig) {
 					c.inc_var(var_object as GlobalVar, config)
 				}
 				Register {
+					c.g.n_error('Register incrementation is not supported yet')
 					// TODO
 					// g.inc()
 				}
 			}
 		}
 		LocalVar {
-			// TODO: size
-			c.g.write8(0x81) // 83 for 1 byte
+			typ := c.g.unwrap(var.typ)
+			mut size_str := 'UNKNOWN'
 			offset := var.offset - config.offset
 			is_far_var := offset > 0x80 || offset < -0x7f
+			match typ {
+				ast.i64_type_idx, ast.u64_type_idx, ast.isize_type_idx, ast.usize_type_idx,
+				ast.int_literal_type_idx {
+					c.g.write16(0xFF48)
+					size_str = 'QWORD'
+				}
+				ast.i32_type_idx, ast.int_type_idx, ast.u32_type_idx, ast.rune_type_idx {
+					c.g.write8(0xFF)
+					size_str = 'DWORD'
+				}
+				ast.i16_type_idx, ast.u16_type_idx {
+					c.g.write8(0xFF)
+					size_str = 'WORD'
+				}
+				ast.i8_type_idx, ast.u8_type_idx, ast.char_type_idx {
+					c.g.write8(0xFE)
+					size_str = 'BYTE'
+				}
+				else {
+					ts := c.g.table.sym(typ.idx_type())
+					c.g.n_error('unsupported type for inc_var ${ts.info}')
+				}
+			}
+
 			c.g.write8(if is_far_var { i32(0x85) } else { i32(0x45) })
 			if is_far_var {
 				c.g.write32(i32((0xffffffff - i64(offset) + 1) % 0x100000000))
 			} else {
 				c.g.write8((0xff - offset + 1) % 0x100)
 			}
-			c.g.write32(1)
-			c.g.println('inc_var `${var.name}`')
+			c.g.println('inc_var ${size_str} `${var.name}`')
 		}
 		GlobalVar {
+			c.g.n_error('Global variables incrementation is not supported yet')
 			// TODO
 		}
 	}
@@ -643,7 +668,7 @@ fn (mut c Amd64) mov_reg_to_var(var Var, r Register, config VarConfig) {
 						c.g.write16(0x8948 + if is_extended_register { i32(4) } else { i32(0) })
 						size_str = 'QWORD'
 					}
-					ast.int_type_idx, ast.u32_type_idx, ast.rune_type_idx {
+					ast.i32_type_idx, ast.int_type_idx, ast.u32_type_idx, ast.rune_type_idx {
 						if is_extended_register {
 							c.g.write8(0x44)
 						}
@@ -694,7 +719,7 @@ fn (mut c Amd64) mov_reg_to_var(var Var, r Register, config VarConfig) {
 			} else {
 				c.g.write8((0xff - offset + 1) % 0x100)
 			}
-			c.g.println('mov ${size_str} PTR [rbp-${int(offset).hex2()}],${reg}')
+			c.g.println('mov ${size_str} PTR [rbp-${int(offset).hex2()}],${reg} ; `${var.name}`')
 		}
 		GlobalVar {
 			// TODO
@@ -746,7 +771,7 @@ fn (mut c Amd64) mov_int_to_var(var Var, integer i32, config VarConfig) {
 					c.g.write16(u16(integer))
 					c.g.println('mov WORD PTR[rbp-${int(offset).hex2()}], ${integer}')
 				}
-				ast.int_type_idx, ast.u32_type_idx, ast.rune_type_idx {
+				ast.i32_type_idx, ast.int_type_idx, ast.u32_type_idx, ast.rune_type_idx {
 					c.g.write8(0xc7)
 					c.g.write8(if is_far_var { i32(0x85) } else { i32(0x45) })
 					if is_far_var {
@@ -832,7 +857,6 @@ fn (mut c Amd64) mov_var_to_reg(reg Register, var Var, config VarConfig) {
 			typ := if config.typ == 0 { var.typ } else { config.typ }
 			size := c.g.get_type_size(typ)
 			is_signed := !typ.is_any_kind_of_pointer() && typ.is_signed()
-
 			instruction, size_str := match true {
 				size == 4 && is_signed {
 					// movsxd rax, DWORD PTR [rbp-0x8]
diff --git a/vlib/v/gen/native/gen.v b/vlib/v/gen/native/gen.v
index 24a488881b..c2fb0c8b8a 100644
--- a/vlib/v/gen/native/gen.v
+++ b/vlib/v/gen/native/gen.v
@@ -710,7 +710,8 @@ fn (mut g Gen) get_type_size(raw_type ast.Type) i32 {
 			ast.u8_type_idx { 1 }
 			ast.i16_type_idx { 2 }
 			ast.u16_type_idx { 2 }
-			ast.int_type_idx { 4 }
+			ast.int_type_idx { 4 } // TODO: change when V will have changed
+			ast.i32_type_idx { 4 }
 			ast.u32_type_idx { 4 }
 			ast.i64_type_idx { 8 }
 			ast.u64_type_idx { 8 }
@@ -722,7 +723,7 @@ fn (mut g Gen) get_type_size(raw_type ast.Type) i32 {
 			ast.float_literal_type_idx { 8 }
 			ast.char_type_idx { 1 }
 			ast.rune_type_idx { 4 }
-			else { 8 }
+			else { g.n_error('unknown type size ${typ}') }
 		}
 	}
 	if typ.is_bool() {
diff --git a/vlib/v/gen/native/stmt.c.v b/vlib/v/gen/native/stmt.c.v
index 2a03a75497..aa6674492f 100644
--- a/vlib/v/gen/native/stmt.c.v
+++ b/vlib/v/gen/native/stmt.c.v
@@ -243,50 +243,56 @@ fn (mut g Gen) for_stmt(node ast.ForStmt) {
 
 fn (mut g Gen) for_in_stmt(node ast.ForInStmt) { // Work on that
 	if node.is_range {
+		g.println('; for ${node.val_var} in range {')
 		// for a in node.cond .. node.high {
 		i := g.code_gen.allocate_var(node.val_var, 8, 0) // iterator variable
+		g.println('; evaluate node.cond for lower bound:')
 		g.expr(node.cond) // outputs the lower loop bound (initial value) to the main reg
 		main_reg := g.code_gen.main_reg()
+		g.println('; move the result to i')
 		g.code_gen.mov_reg_to_var(LocalVar{i, ast.i64_type_idx, node.val_var}, main_reg) // i = node.cond // initial value
 
 		start := g.pos() // label-begin:
 		start_label := g.labels.new_label()
+
+		g.println('; check iterator against upper loop bound')
 		g.code_gen.mov_var_to_reg(main_reg, LocalVar{i, ast.i64_type_idx, node.val_var})
 		g.code_gen.push(main_reg) // put the iterator on the stack
 		g.expr(node.high) // final value (upper bound) to the main reg
 		g.code_gen.cmp_to_stack_top(main_reg)
 		jump_addr := g.code_gen.cjmp(.jge) // leave loop i >= upper bound
-
 		end_label := g.labels.new_label()
 		g.labels.patches << LabelPatch{
 			id:  end_label
 			pos: jump_addr
 		}
-		g.println('; jump to label ${end_label}')
+		g.println('; jump to label ${end_label} (end_label)')
 		g.labels.branches << BranchLabel{
 			name:  node.label
 			start: start_label
 			end:   end_label
 		}
+
 		g.stmts(node.stmts) // writes the actual body of the loop
 		g.labels.addrs[start_label] = g.pos()
-		g.println('; label ${start_label}')
+		g.println('; label ${start_label} (start_label)')
 		g.code_gen.inc_var(LocalVar{i, ast.i64_type_idx, node.val_var})
 		g.labels.branches.pop()
 		g.code_gen.jmp_back(start) // loops
 		g.labels.addrs[end_label] = g.pos()
-		g.println('; label ${end_label}')
+		g.println('; label ${end_label} (end_label)')
+		g.println('; for ${node.val_var} in range }')
 		/*
-		} else if node.kind == .array {
+	} else if node.kind == .array {
 	} else if node.kind == .array_fixed {
 	} else if node.kind == .map {
 	} else if node.kind == .string {
 	} else if node.kind == .struct {
 	} else if it.kind in [.array, .string] || it.cond_type.has_flag(.variadic) {
 	} else if it.kind == .map {
-		*/
+	*/
 	} else {
-		g.v_error('for-in statement is not yet implemented', node.pos)
+		g.n_error('for-in ${node.kind} statement is not yet implemented')
 	}
 }
 
diff --git a/vlib/v/gen/native/tests/inc.vv b/vlib/v/gen/native/tests/inc.vv
new file mode 100644
index 0000000000..4147936d4a
--- /dev/null
+++ b/vlib/v/gen/native/tests/inc.vv
@@ -0,0 +1,48 @@
+fn signed_inc_test() {
+	mut a := i64(1)
+	println(a)
+	a++
+	println(a)
+	mut b := i32(1)
+	println(b)
+	b++
+	println(b)
+	mut c := i16(1)
+	println(c)
+	c++
+	println(c)
+	mut d := i8(1)
+	println(d)
+	d++
+	println(d)
+	mut e := int(1)
+	println(e)
+	e++
+	println(e)
+
+	// TODO: negative inc test (when negative ints will be supported)
+}
+
+fn unsigned_inc_test() {
+	mut f := u64(1)
+	println(f)
+	f++
+	println(f)
+	mut g := u32(1)
+	println(g)
+	g++
+	println(g)
+	mut h := u16(1)
+	println(h)
+	h++
+	println(h)
+	mut i := u8(1)
+	println(i)
+	i++
+	println(i)
+}
+
+fn main() {
+	signed_inc_test()
+	unsigned_inc_test()
+}
diff --git a/vlib/v/gen/native/tests/inc.vv.out b/vlib/v/gen/native/tests/inc.vv.out
new file mode 100644
index 0000000000..06bce09492
--- /dev/null
+++ b/vlib/v/gen/native/tests/inc.vv.out
@@ -0,0 +1,18 @@
+1
+2
+1
+2
+1
+2
+1
+2
+1
+2
+1
+2
+1
+2
+1
+2
+1
+2
diff --git a/vlib/v/gen/native/tests/native_test.v b/vlib/v/gen/native/tests/native_test.v
index eead96eb3e..92129a8c22 100644
--- a/vlib/v/gen/native/tests/native_test.v
+++ b/vlib/v/gen/native/tests/native_test.v
@@ -80,6 +80,7 @@ fn test_native() {
 			eprintln('------------------------------------------------')
 			eprintln('> tmperrfile: ${tmperrfile}, exists: ${os.exists(tmperrfile)}, content:')
 			errstr := os.read_file(tmperrfile) or { '' }
+			eprintln('------------------------------------------------')
 			eprintln(errstr)
 			eprintln('------------------------------------------------')
 			eprintln('')