diff --git a/slige/compiler/ast/ast.ts b/slige/compiler/ast/ast.ts
index ea61696..24bc778 100644
--- a/slige/compiler/ast/ast.ts
+++ b/slige/compiler/ast/ast.ts
@@ -179,10 +179,10 @@ export type RefType = "ref" | "ptr";
 export type UnaryType = "not" | "-";
 export type BinaryType =
     | "+"
-    | "*"
-    | "=="
     | "-"
+    | "*"
     | "/"
+    | "=="
     | "!="
     | "<"
     | ">"
diff --git a/slige/compiler/check/checker.ts b/slige/compiler/check/checker.ts
index d31b518..bc26418 100644
--- a/slige/compiler/check/checker.ts
+++ b/slige/compiler/check/checker.ts
@@ -141,58 +141,12 @@ export class Checker {
                 return this.checkCallExpr(expr, k, expected);
             case "unary":
                 return todo();
-            case "binary": {
-                const res = this.resolveTys(
-                    this.exprTy(k.left),
-                    this.exprTy(k.right),
-                );
-                if (!res.ok) {
-                    this.exprTys.set(expr.id, Ty({ tag: "error" }));
-                    this.report(res.val, expr.span);
-                    return Ty({ tag: "error" });
-                }
-                this.exprTys.set(expr.id, res.val);
-                return res.val;
-            }
-            case "block": {
-                const ty = this.checkBlock(k.block, expected);
-                return ty;
-            }
-            case "if": {
-                const cond = this.exprTy(k.cond);
-                const condRes = this.resolveTys(cond, Ty({ tag: "bool" }));
-                if (!condRes.ok) {
-                    this.exprTys.set(expr.id, Ty({ tag: "error" }));
-                    this.report("if-condition must be a boolean", k.cond.span);
-                    return Ty({ tag: "error" });
-                }
-                const truthy = this.exprTy(k.truthy);
-                if (!k.falsy) {
-                    const truthyRes = this.resolveTys(
-                        truthy,
-                        Ty({ tag: "null" }),
-                    );
-                    if (!truthyRes.ok) {
-                        this.exprTys.set(expr.id, Ty({ tag: "error" }));
-                        this.report(
-                            "if there isn't a falsy-clause, then the truthy clause must evaluate to null",
-                            k.truthy.span,
-                        );
-                        return Ty({ tag: "error" });
-                    }
-                    this.exprTys.set(expr.id, Ty({ tag: "null" }));
-                    return Ty({ tag: "null" });
-                }
-                const falsy = this.exprTy(k.falsy);
-                const bothRes = this.resolveTys(truthy, falsy);
-                if (!bothRes.ok) {
-                    this.exprTys.set(expr.id, Ty({ tag: "error" }));
-                    this.report(bothRes.val, k.truthy.span);
-                    return Ty({ tag: "error" });
-                }
-                this.exprTys.set(expr.id, bothRes.val);
-                return bothRes.val;
-            }
+            case "binary":
+                return this.checkBinaryExpr(expr, k, expected);
+            case "block":
+                return this.checkBlock(k.block, expected);
+            case "if":
+                return this.checkIfExpr(expr, k, expected);
             case "loop":
                 return todo();
             case "while":
@@ -261,15 +215,110 @@ export class Checker {
             );
             return Ty({ tag: "error" });
         }
-        const _args = kind.args.map((arg, i) =>
-            this.checkExpr(arg, paramTys[i])
-        );
+        for (const [i, arg] of kind.args.entries()) {
+            this.checkExpr(arg, paramTys[i]);
+        }
 
         const ty = fnTy.kind.returnTy;
         this.exprTys.set(expr.id, ty);
         return ty;
     }
 
+    private checkBinaryExpr(
+        expr: ast.Expr,
+        kind: ast.BinaryExpr,
+        expected: Ty,
+    ): Ty {
+        switch (kind.binaryType) {
+            case "+":
+            case "-":
+            case "*":
+            case "/": {
+                const operandRes = this.resolveTys(
+                    this.exprTy(kind.left),
+                    this.exprTy(kind.right),
+                );
+                if (!operandRes.ok) {
+                    this.exprTys.set(expr.id, Ty({ tag: "error" }));
+                    this.report(operandRes.val, expr.span);
+                    return Ty({ tag: "error" });
+                }
+                const operatorRes = this.resolveTys(
+                    operandRes.val,
+                    Ty({ tag: "int" }),
+                );
+                if (!operatorRes.ok) {
+                    this.exprTys.set(expr.id, Ty({ tag: "error" }));
+                    this.report(operatorRes.val, expr.span);
+                    return Ty({ tag: "error" });
+                }
+                this.exprTys.set(expr.id, operatorRes.val);
+                return operandRes.val;
+            }
+            case "==":
+            case "!=":
+            case "<":
+            case ">":
+            case "<=":
+            case ">=":
+            case "or":
+            case "and": {
+                const operandRes = this.resolveTys(
+                    this.exprTy(kind.left),
+                    this.exprTy(kind.right),
+                );
+                if (!operandRes.ok) {
+                    this.exprTys.set(expr.id, Ty({ tag: "error" }));
+                    this.report(operandRes.val, expr.span);
+                    return Ty({ tag: "error" });
+                }
+                const ty = Ty({ tag: "bool" });
+                this.exprTys.set(expr.id, ty);
+                return ty;
+            }
+        }
+    }
+
+    private checkIfExpr(
+        expr: ast.Expr,
+        kind: ast.IfExpr,
+        expected: Ty,
+    ): Ty {
+        const cond = this.exprTy(kind.cond);
+        const condRes = this.resolveTys(cond, Ty({ tag: "bool" }));
+        if (!condRes.ok) {
+            this.exprTys.set(expr.id, Ty({ tag: "error" }));
+            this.report("if-condition must be a boolean", kind.cond.span);
+            return Ty({ tag: "error" });
+        }
+        const truthy = this.exprTy(kind.truthy);
+        if (!kind.falsy) {
+            const truthyRes = this.resolveTys(
+                truthy,
+                Ty({ tag: "null" }),
+            );
+            if (!truthyRes.ok) {
+                this.exprTys.set(expr.id, Ty({ tag: "error" }));
+                this.report(
+                    "if there isn't a falsy-clause, then the truthy clause must evaluate to null",
+                    kind.truthy.span,
+                );
+                return Ty({ tag: "error" });
+            }
+            this.exprTys.set(expr.id, Ty({ tag: "null" }));
+            return Ty({ tag: "null" });
+        }
+        const falsy = this.exprTy(kind.falsy);
+        const bothRes = this.resolveTys(truthy, falsy);
+        if (!bothRes.ok) {
+            this.exprTys.set(expr.id, Ty({ tag: "error" }));
+            this.report(bothRes.val, kind.truthy.span);
+            return Ty({ tag: "error" });
+        }
+        this.exprTys.set(expr.id, bothRes.val);
+        return bothRes.val;
+    }
+
     private tyTy(ty: ast.Ty): Ty {
         return this.tyTys.get(ty.id) ||
             this.checkTy(ty);
diff --git a/slige/compiler/parse/parser.ts b/slige/compiler/parse/parser.ts
index 5982b50..5569d82 100644
--- a/slige/compiler/parse/parser.ts
+++ b/slige/compiler/parse/parser.ts
@@ -24,7 +24,7 @@ import {
     TyKind,
     UnaryType,
 } from "@slige/ast";
-import { Ctx, File as CtxFile, Pos, Res, Span, todo } from "@slige/common";
+import { Ctx, File as CtxFile, Res, Span } from "@slige/common";
 import { Lexer } from "./lexer.ts";
 import { TokenIter } from "./token.ts";
 import { SigFilter } from "./token.ts";
@@ -726,11 +726,10 @@ export class Parser {
     }
 
     private parseOr(rs: ExprRestricts): Expr {
-        const pos = this.span();
         let left = this.parseAnd(rs);
         while (true) {
             if (this.test("or")) {
-                left = this.parBinTail(left, pos, rs, this.parseAnd, "or");
+                left = this.parBinTail(left, rs, this.parseAnd, "or");
             } else {
                 break;
             }
@@ -739,11 +738,10 @@ export class Parser {
     }
 
     private parseAnd(rs: ExprRestricts): Expr {
-        const pos = this.span();
-        let left = this.parseEq(rs);
+        let left = this.parseEquality(rs);
         while (true) {
             if (this.test("and")) {
-                left = this.parBinTail(left, pos, rs, this.parseEq, "and");
+                left = this.parBinTail(left, rs, this.parseEquality, "and");
             } else {
                 break;
             }
@@ -751,36 +749,33 @@ export class Parser {
         return left;
     }
 
-    private parseEq(rs: ExprRestricts): Expr {
-        const pos = this.span();
+    private parseEquality(rs: ExprRestricts): Expr {
         const left = this.parseComparison(rs);
         if (this.test("==") || this.test("!=")) {
             const op = this.current().type as BinaryType;
-            return this.parBinTail(left, pos, rs, this.parseComparison, op);
+            return this.parBinTail(left, rs, this.parseComparison, op);
         }
         return left;
     }
 
     private parseComparison(rs: ExprRestricts): Expr {
-        const pos = this.span();
         const left = this.parseAddSub(rs);
         if (
             this.test("<") || this.test(">") || this.test("<=") ||
             this.test(">=")
         ) {
             const op = this.current().type as BinaryType;
-            return this.parBinTail(left, pos, rs, this.parseAddSub, op);
+            return this.parBinTail(left, rs, this.parseAddSub, op);
         }
         return left;
     }
 
     private parseAddSub(rs: ExprRestricts): Expr {
-        const pos = this.span();
         let left = this.parseMulDiv(rs);
         while (true) {
             if (this.test("+") || this.test("-")) {
                 const op = this.current().type as BinaryType;
-                left = this.parBinTail(left, pos, rs, this.parseMulDiv, op);
+                left = this.parBinTail(left, rs, this.parseMulDiv, op);
                 continue;
             }
             break;
@@ -789,12 +784,11 @@ export class Parser {
     }
 
     private parseMulDiv(rs: ExprRestricts): Expr {
-        const pos = this.span();
         let left = this.parsePrefix(rs);
         while (true) {
             if (this.test("*") || this.test("/")) {
                 const op = this.current().type as BinaryType;
-                left = this.parBinTail(left, pos, rs, this.parsePrefix, op);
+                left = this.parBinTail(left, rs, this.parsePrefix, op);
                 continue;
             }
             break;
@@ -804,7 +798,6 @@ export class Parser {
 
     private parBinTail(
         left: Expr,
-        span: Span,
         rs: ExprRestricts,
         parseRight: (this: Parser, rs: ExprRestricts) => Expr,
         binaryType: BinaryType,
@@ -813,7 +806,7 @@ export class Parser {
         const right = parseRight.call(this, rs);
         return this.expr(
             { tag: "binary", binaryType, left, right },
-            span,
+            Span.fromto(left.span, right.span),
         );
     }
 
diff --git a/slige/compiler/program.slg b/slige/compiler/program.slg
index fe7847f..863a1a4 100644
--- a/slige/compiler/program.slg
+++ b/slige/compiler/program.slg
@@ -7,7 +7,7 @@ fn main() {
     let foo = 5;
     let bar = 7 + foo;
 
-    if foo {} else {}
+    if foo == 5 {} else {}
 
     let c = add(foo, bar);
 }