diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 35efcccbb2..4fcf4664db 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -103,7 +103,7 @@ jobs:
         run: |
           ./v tutorials/building_a_simple_web_blog_with_vweb/code/blog
       - name: Build cmd/tools/fast
-        run: cd cmd/tools/fast && v fast.v #&& ./fast
+        run: cd cmd/tools/fast && ../../../v fast.v && ./fast
 
   ubuntu-tcc-boehm-gc:
     runs-on: ubuntu-20.04
diff --git a/vlib/math/big/big.v b/vlib/math/big/big.v
index 4a182e2134..6e9ac668ed 100644
--- a/vlib/math/big/big.v
+++ b/vlib/math/big/big.v
@@ -119,8 +119,8 @@ pub fn from_string(input string) Number {
 }
 
 // .int() converts (a small) big.Number `n` to an ordinary integer.
-pub fn (n Number) int() int {
-	r := C.bignum_to_int(&n)
+pub fn (n &Number) int() int {
+	r := C.bignum_to_int(n)
 	return r
 }
 
@@ -129,7 +129,7 @@ const (
 )
 
 // .str returns a decimal representation of the big unsigned integer number n.
-pub fn (n Number) str() string {
+pub fn (n &Number) str() string {
 	if n.is_zero() {
 		return '0'
 	}
@@ -145,13 +145,13 @@ pub fn (n Number) str() string {
 }
 
 // .hexstr returns a hexadecimal representation of the bignum `n`
-pub fn (n Number) hexstr() string {
+pub fn (n &Number) hexstr() string {
 	mut buf := [8192]byte{}
 	mut s := ''
 	unsafe {
 		bp := &buf[0]
 		// NB: C.bignum_to_string(), returns the HEXADECIMAL representation of the bignum n
-		C.bignum_to_string(&n, &char(bp), 8192)
+		C.bignum_to_string(n, &char(bp), 8192)
 		s = tos_clone(bp)
 	}
 	if s.len == 0 {
@@ -162,33 +162,33 @@ pub fn (n Number) hexstr() string {
 
 // //////////////////////////////////////////////////////////
 // overloaded ops for the numbers:
-pub fn (a Number) + (b Number) Number {
+pub fn (a &Number) + (b &Number) Number {
 	c := Number{}
-	C.bignum_add(&a, &b, &c)
+	C.bignum_add(a, b, &c)
 	return c
 }
 
-pub fn (a Number) - (b Number) Number {
+pub fn (a &Number) - (b &Number) Number {
 	c := Number{}
-	C.bignum_sub(&a, &b, &c)
+	C.bignum_sub(a, b, &c)
 	return c
 }
 
-pub fn (a Number) * (b Number) Number {
+pub fn (a &Number) * (b &Number) Number {
 	c := Number{}
-	C.bignum_mul(&a, &b, &c)
+	C.bignum_mul(a, b, &c)
 	return c
 }
 
-pub fn (a Number) / (b Number) Number {
+pub fn (a &Number) / (b &Number) Number {
 	c := Number{}
-	C.bignum_div(&a, &b, &c)
+	C.bignum_div(a, b, &c)
 	return c
 }
 
-pub fn (a Number) % (b Number) Number {
+pub fn (a &Number) % (b &Number) Number {
 	c := Number{}
-	C.bignum_mod(&a, &b, &c)
+	C.bignum_mod(a, b, &c)
 	return c
 }
 
@@ -199,73 +199,73 @@ pub fn divmod(a &Number, b &Number, c &Number) Number {
 }
 
 // //////////////////////////////////////////////////////////
-pub fn cmp(a Number, b Number) int {
-	return C.bignum_cmp(&a, &b)
+pub fn cmp(a &Number, b &Number) int {
+	return C.bignum_cmp(a, b)
 }
 
-pub fn (a Number) is_zero() bool {
-	return C.bignum_is_zero(&a) != 0
+pub fn (a &Number) is_zero() bool {
+	return C.bignum_is_zero(a) != 0
 }
 
 pub fn (mut a Number) inc() {
-	C.bignum_inc(a)
+	C.bignum_inc(&a)
 }
 
 pub fn (mut a Number) dec() {
-	C.bignum_dec(a)
+	C.bignum_dec(&a)
 }
 
-pub fn pow(a Number, b Number) Number {
+pub fn pow(a &Number, b &Number) Number {
 	c := Number{}
-	C.bignum_pow(&a, &b, &c)
+	C.bignum_pow(a, b, &c)
 	return c
 }
 
-pub fn (a Number) isqrt() Number {
+pub fn (a &Number) isqrt() Number {
 	b := Number{}
-	C.bignum_isqrt(&a, &b)
+	C.bignum_isqrt(a, &b)
 	return b
 }
 
 // //////////////////////////////////////////////////////////
-pub fn b_and(a Number, b Number) Number {
+pub fn b_and(a &Number, b &Number) Number {
 	c := Number{}
-	C.bignum_and(&a, &b, &c)
+	C.bignum_and(a, b, &c)
 	return c
 }
 
-pub fn b_or(a Number, b Number) Number {
+pub fn b_or(a &Number, b &Number) Number {
 	c := Number{}
-	C.bignum_or(&a, &b, &c)
+	C.bignum_or(a, b, &c)
 	return c
 }
 
-pub fn b_xor(a Number, b Number) Number {
+pub fn b_xor(a &Number, b &Number) Number {
 	c := Number{}
-	C.bignum_xor(&a, &b, &c)
+	C.bignum_xor(a, b, &c)
 	return c
 }
 
-pub fn (a Number) lshift(nbits int) Number {
+pub fn (a &Number) lshift(nbits int) Number {
 	b := Number{}
-	C.bignum_lshift(&a, &b, nbits)
+	C.bignum_lshift(a, &b, nbits)
 	return b
 }
 
-pub fn (a Number) rshift(nbits int) Number {
+pub fn (a &Number) rshift(nbits int) Number {
 	b := Number{}
-	C.bignum_rshift(&a, &b, nbits)
+	C.bignum_rshift(a, &b, nbits)
 	return b
 }
 
-pub fn (a Number) clone() Number {
+pub fn (a &Number) clone() Number {
 	b := Number{}
-	C.bignum_assign(&b, &a)
+	C.bignum_assign(&b, a)
 	return b
 }
 
 // //////////////////////////////////////////////////////////
-pub fn factorial(nn Number) Number {
+pub fn factorial(nn &Number) Number {
 	mut n := nn.clone()
 	mut a := nn.clone()
 	n.dec()
@@ -291,9 +291,9 @@ pub fn fact(n int) Number {
 // Example: assert big.from_int(1).bytes()[0] == byte(0x01)
 // Example: assert big.from_int(1024).bytes()[1] == byte(0x04)
 // Example: assert big.from_int(1048576).bytes()[2] == byte(0x10)
-pub fn (n Number) bytes() []byte {
+pub fn (n &Number) bytes() []byte {
 	mut res := []byte{len: 128, init: 0}
-	unsafe { C.memcpy(res.data, &n, 128) }
+	unsafe { C.memcpy(res.data, n, 128) }
 	return res
 }
 
@@ -304,9 +304,9 @@ pub fn (n Number) bytes() []byte {
 // Example: assert big.from_int(1).bytes_trimmed() == [byte(0x01)]
 // Example: assert big.from_int(1024).bytes_trimmed() == [byte(0x00), 0x04]
 // Example: assert big.from_int(1048576).bytes_trimmed() == [byte(0x00), 0x00, 0x10]
-pub fn (n Number) bytes_trimmed() []byte {
+pub fn (n &Number) bytes_trimmed() []byte {
 	mut res := []byte{len: 128, init: 0}
-	unsafe { C.memcpy(res.data, &n, 128) }
+	unsafe { C.memcpy(res.data, n, 128) }
 	mut non_zero_idx := 127
 	for ; non_zero_idx >= 0; non_zero_idx-- {
 		if res[non_zero_idx] != 0 {
diff --git a/vlib/math/big/big_test.v b/vlib/math/big/big_test.v
index 63982cadcc..c2b3cc6cc5 100644
--- a/vlib/math/big/big_test.v
+++ b/vlib/math/big/big_test.v
@@ -31,6 +31,11 @@ fn test_plus() {
 	assert (big.from_u64(1024) + big.from_u64(1024)).hexstr() == '800'
 	a += b
 	assert a.hexstr() == '5'
+	a.inc()
+	assert a.hexstr() == '6'
+	a.dec()
+	a.dec()
+	assert a.hexstr() == '4'
 }
 
 fn test_minus() {
diff --git a/vlib/v/gen/c/cgen.v b/vlib/v/gen/c/cgen.v
index 155f2b4057..b0691f9bf3 100644
--- a/vlib/v/gen/c/cgen.v
+++ b/vlib/v/gen/c/cgen.v
@@ -2606,6 +2606,8 @@ fn (mut g Gen) gen_assign_stmt(assign_stmt ast.AssignStmt) {
 			}
 			mut str_add := false
 			mut op_overloaded := false
+			mut op_expected_left := ast.Type(0)
+			mut op_expected_right := ast.Type(0)
 			if var_type == ast.string_type_idx && assign_stmt.op == .plus_assign {
 				if left is ast.IndexExpr {
 					// a[0] += str => `array_set(&a, 0, &(string[]) {string__plus(...))})`
@@ -2633,6 +2635,14 @@ fn (mut g Gen) gen_assign_stmt(assign_stmt ast.AssignStmt) {
 				}
 				g.expr(left)
 				g.write(' = ${styp}_${util.replace_op(extracted_op)}(')
+				method := g.table.type_find_method(left_sym, extracted_op) or {
+					// the checker will most likely have found this, already...
+					g.error('assignemnt operator `$extracted_op=` used but no `$extracted_op` method defined',
+						assign_stmt.pos)
+					ast.Fn{}
+				}
+				op_expected_left = method.params[0].typ
+				op_expected_right = method.params[1].typ
 				op_overloaded = true
 			}
 			if right_sym.kind == .function && is_decl {
@@ -2681,10 +2691,14 @@ fn (mut g Gen) gen_assign_stmt(assign_stmt ast.AssignStmt) {
 					g.prevent_sum_type_unwrapping_once = true
 				}
 				if !is_fixed_array_var || is_decl {
-					if !is_decl && left.is_auto_deref_var() {
-						g.write('*')
+					if op_overloaded {
+						g.op_arg(left, op_expected_left, var_type)
+					} else {
+						if !is_decl && left.is_auto_deref_var() {
+							g.write('*')
+						}
+						g.expr(left)
 					}
-					g.expr(left)
 				}
 			}
 			if is_inside_ternary && is_decl {
@@ -2770,7 +2784,11 @@ fn (mut g Gen) gen_assign_stmt(assign_stmt ast.AssignStmt) {
 					if assign_stmt.has_cross_var {
 						g.gen_cross_tmp_variable(assign_stmt.left, val)
 					} else {
-						g.expr_with_cast(val, val_type, var_type)
+						if op_overloaded {
+							g.op_arg(val, op_expected_right, val_type)
+						} else {
+							g.expr_with_cast(val, val_type, var_type)
+						}
 					}
 				}
 			}
diff --git a/vlib/v/gen/c/fn.v b/vlib/v/gen/c/fn.v
index 189bcac634..c408f210a3 100644
--- a/vlib/v/gen/c/fn.v
+++ b/vlib/v/gen/c/fn.v
@@ -1272,6 +1272,7 @@ fn (mut g Gen) ref_or_deref_arg(arg ast.CallArg, expected_type ast.Type, lang as
 		g.checker_bug('ref_or_deref_arg expected_type is 0', arg.pos)
 	}
 	exp_sym := g.table.get_type_symbol(expected_type)
+	mut needs_closing := false
 	if arg.is_mut && !arg_is_ptr {
 		g.write('&/*mut*/')
 	} else if arg_is_ptr && !expr_is_ptr {
@@ -1303,7 +1304,12 @@ fn (mut g Gen) ref_or_deref_arg(arg ast.CallArg, expected_type ast.Type, lang as
 			deref_sym := g.table.get_type_symbol(expected_deref_type)
 			if !((arg_typ_sym.kind == .function)
 				|| deref_sym.kind in [.sum_type, .interface_]) && lang != .c {
-				g.write('(voidptr)&/*qq*/')
+				if arg.expr.is_lvalue() {
+					g.write('(voidptr)&/*qq*/')
+				} else {
+					needs_closing = true
+					g.write('ADDR(${g.typ(expected_deref_type)}/*qq*/, ')
+				}
 			}
 		}
 	} else if arg.typ.has_flag(.shared_f) && !expected_type.has_flag(.shared_f) {
@@ -1315,6 +1321,9 @@ fn (mut g Gen) ref_or_deref_arg(arg ast.CallArg, expected_type ast.Type, lang as
 		return
 	}
 	g.expr_with_cast(arg.expr, arg.typ, expected_type)
+	if needs_closing {
+		g.write(')')
+	}
 }
 
 fn (mut g Gen) is_gui_app() bool {
diff --git a/vlib/v/gen/c/infix_expr.v b/vlib/v/gen/c/infix_expr.v
index e457df27c4..901e604bb6 100644
--- a/vlib/v/gen/c/infix_expr.v
+++ b/vlib/v/gen/c/infix_expr.v
@@ -425,21 +425,19 @@ fn (mut g Gen) infix_expr_is_op(node ast.InfixExpr) {
 fn (mut g Gen) infix_expr_arithmetic_op(node ast.InfixExpr) {
 	left := g.unwrap(node.left_type)
 	right := g.unwrap(node.right_type)
-	has_operator_overloading := g.table.type_has_method(left.sym, node.op.str())
-	if left.sym.kind == right.sym.kind && has_operator_overloading {
-		g.write(g.typ(left.typ.set_nr_muls(0)))
-		g.write('_')
-		g.write(util.replace_op(node.op.str()))
-		g.write('(')
-		g.write('*'.repeat(left.typ.nr_muls()))
-		g.expr(node.left)
-		g.write(', ')
-		g.write('*'.repeat(right.typ.nr_muls()))
-		g.expr(node.right)
-		g.write(')')
-	} else {
+	method := g.table.type_find_method(left.sym, node.op.str()) or {
 		g.gen_plain_infix_expr(node)
+		return
 	}
+	left_styp := g.typ(left.typ.set_nr_muls(0))
+	g.write(left_styp)
+	g.write('_')
+	g.write(util.replace_op(node.op.str()))
+	g.write('(')
+	g.op_arg(node.left, method.params[0].typ, left.typ)
+	g.write(', ')
+	g.op_arg(node.right, method.params[1].typ, right.typ)
+	g.write(')')
 }
 
 // infix_expr_left_shift_op generates code for the `<<` operator
@@ -515,6 +513,29 @@ fn (mut g Gen) gen_plain_infix_expr(node ast.InfixExpr) {
 	g.expr_with_cast(node.right, node.right_type, node.left_type)
 }
 
+fn (mut g Gen) op_arg(expr ast.Expr, expected ast.Type, got ast.Type) {
+	mut needs_closing := false
+	mut nr_muls := got.nr_muls()
+	if expected.is_ptr() {
+		if nr_muls > 0 {
+			nr_muls--
+		} else {
+			if expr.is_lvalue() {
+				g.write('&')
+			} else {
+				styp := g.typ(got.set_nr_muls(0))
+				g.write('ADDR($styp, ')
+				needs_closing = true
+			}
+		}
+	}
+	g.write('*'.repeat(nr_muls))
+	g.expr(expr)
+	if needs_closing {
+		g.write(')')
+	}
+}
+
 struct GenSafeIntegerCfg {
 	op            token.Kind
 	reverse       bool