diff --git a/lexer.v b/lexer.v
index 8f81a84..a5f3932 100644
--- a/lexer.v
+++ b/lexer.v
@@ -25,6 +25,7 @@ enum TokenType as u8 {
 	minus
 	star
 	slash
+	percent
 	equals
 	less
 	greater
@@ -36,6 +37,7 @@ enum TokenType as u8 {
 	minus_eq
 	star_eq
 	slash_eq
+	percent_eq
 	increment
 	decrement
 	lparen
@@ -73,6 +75,7 @@ fn toktype_from_delimiter(delimiter string) TokenType {
 		'-' {.minus}
 		'*' {.star}
 		'/' {.slash}
+		'%' {.percent}
 		'=' {.equals}
 		'<' {.less}
 		'>' {.greater}
@@ -88,6 +91,7 @@ fn toktype_from_delimiter(delimiter string) TokenType {
 		'-=' {.minus_eq}
 		'*=' {.star_eq}
 		'/=' {.slash_eq}
+		'%=' {.percent_eq}
 		'++' {.increment}
 		'--' {.decrement}
 		else {.unknown}
@@ -186,7 +190,7 @@ fn lex(input string) ?[]Token {
 				mut tok_str := input[right].ascii_str()
 				if right + 1 < input.len {
 					combined := input.substr(right, right + 2)
-					if combined in ['==', '>=', '<=', '!=', '+=', '-=', '*=', '/=', '++', '--'] {
+					if combined in ['==', '>=', '<=', '!=', '+=', '-=', '*=', '/=', '%=', '++', '--'] {
 						tok_str = combined
 						right++
 					}
diff --git a/one b/one
index 711b1ec..6074933 100755
Binary files a/one and b/one differ
diff --git a/parser.v b/parser.v
index 680aa95..2a86262 100644
--- a/parser.v
+++ b/parser.v
@@ -18,10 +18,10 @@ enum Precedence {
 
 fn (p Parser) get_precedence(tok_type TokenType) Precedence {
 	return match tok_type {
-    .equals, .plus_eq, .minus_eq, .star_eq, .slash_eq 			{ .assignment }
+    .equals, .plus_eq, .minus_eq, .star_eq, .slash_eq, .percent_eq { .assignment }
     .eq_eq, .not_eq, .less_eq, .greater_eq, .less, .greater { .comparison }
     .plus, .minus                                    				{ .sum }
-    .star, .slash                                    				{ .product }
+    .star, .slash, .percent                         				{ .product }
 		.dot                                             				{ .access  }
 		.increment, .decrement                                  { .suffix }
     else                                             				{ .base}
@@ -467,12 +467,14 @@ fn (mut p Parser) parse_unary_left(op string) UnaryExpr {
 
 fn (mut p Parser) parse_binary(left Expr, op string, prec Precedence) BinaryExpr {
 
-	if op in ['=', '+=', '-=', '*=', '/='] {
+	if op in ['=', '+=', '-=', '*=', '/=', '%='] {
 		if p.get_expr_is_immutable(left) {
 			parse_error("Cannot assign to immutable expression ${left}")
 		}
 	}
 
+	dump(op)
+
 	right := p.parse_expr(prec)
 	binary_expr := BinaryExpr{left, op, right}
 
@@ -572,7 +574,15 @@ fn (mut p Parser) get_expr_type(expr Expr) string {
 fn (mut p Parser) is_op_valid_for_type(type string, op string) bool {
 	global := ['=', '==', '!=']
 	mut legal_ops := match type {
-		'int', 'real' {['+', '-', '*', '/', '<', '>', '<=', '>=', '++', '--', '+=', '-=', '*=', '/=', '++', '--']}
+		'int' {[
+			'+', '-', '*', '/', '%', '<', '>', '<=',
+			'>=', '++', '--', '+=', '-=', '*=', '/=',
+			'%='
+		]}
+		'real' {[
+			'+', '-', '*', '/', '<', '>', '<=', '>=',
+			'++', '--', '+=', '-=', '*=', '/=',
+		]}
 		'bool' {['=']}
 		else {[]}
 	}