diff --git a/bootstrap/emit.cc b/bootstrap/emit.cc
index e121da8..dcada32 100644
--- a/bootstrap/emit.cc
+++ b/bootstrap/emit.cc
@@ -45,7 +45,7 @@ std::any EmitVisitor::visitStatement(xlangParser::StatementContext *ctx) {
     int block = blockcount++;
     output << "@if" << block << "_expr" << std::endl;
     tmpcount = 0;
-    visitExpr(ctx->expr());
+    visitCondition(ctx->condition());
     output << "  jnz " << last << ", @if" << block << "_then, @if" << block
            << "_else" << std::endl;
     output << "@if" << block << "_then" << std::endl;
@@ -62,7 +62,7 @@ std::any EmitVisitor::visitStatement(xlangParser::StatementContext *ctx) {
     int block = blockcount++;
     output << "@while" << block << "_expr" << std::endl;
     tmpcount = 0;
-    visitExpr(ctx->expr());
+    visitCondition(ctx->condition());
     output << "  jnz " << last << ", @while" << block << "_body, @while"
            << block << "_end" << std::endl;
     output << "@while" << block << "_body" << std::endl;
@@ -100,20 +100,47 @@ std::any EmitVisitor::visitStatement(xlangParser::StatementContext *ctx) {
     return {};                                                         \
   }
 
-std::any EmitVisitor::visitExpr(xlangParser::ExprContext *ctx) {
-  OPERATOR(Less, visitSum, sum(0), visitSum, sum(1), "csltw");
-  OPERATOR(LessEqual, visitSum, sum(0), visitSum, sum(1), "cslew");
-  OPERATOR(Greater, visitSum, sum(0), visitSum, sum(1), "csgtw");
-  OPERATOR(GreaterEqual, visitSum, sum(0), visitSum, sum(1), "csgew");
-  OPERATOR(Equal, visitSum, sum(0), visitSum, sum(1), "ceqw");
-  OPERATOR(NotEqual, visitSum, sum(0), visitSum, sum(1), "cnew");
-  visitSum(ctx->sum(0));
+std::any EmitVisitor::visitCondition(xlangParser::ConditionContext *ctx) {
+  OPERATOR(And, visitCondition, condition(), visitBoolean, boolean(), "and");
+  OPERATOR(Or, visitCondition, condition(), visitBoolean, boolean(), "or");
+  OPERATOR(Xor, visitCondition, condition(), visitBoolean, boolean(), "xor");
+  visitBoolean(ctx->boolean());
   return {};
 }
 
-std::any EmitVisitor::visitSum(xlangParser::SumContext *ctx) {
-  OPERATOR(Plus, visitSum, sum(), visitTerm, term(), "add");
-  OPERATOR(Minus, visitSum, sum(), visitTerm, term(), "sub");
+std::any EmitVisitor::visitBoolean(xlangParser::BooleanContext *ctx) {
+  if (ctx->Not()) {
+    visitBoolean(ctx->boolean());
+    std::string b = last;
+    output << "  " << tmp() << " = w xor 1, " << b << std::endl;
+    return {};
+  }
+  OPERATOR(Less, visitExpr, expr(0), visitExpr, expr(1), "csltw");
+  OPERATOR(LessEqual, visitExpr, expr(0), visitExpr, expr(1), "cslew");
+  OPERATOR(Greater, visitExpr, expr(0), visitExpr, expr(1), "csgtw");
+  OPERATOR(GreaterEqual, visitExpr, expr(0), visitExpr, expr(1), "csgew");
+  OPERATOR(Equal, visitExpr, expr(0), visitExpr, expr(1), "ceqw");
+  OPERATOR(NotEqual, visitExpr, expr(0), visitExpr, expr(1), "cnew");
+  if (ctx->True()) {
+    last = "1";
+    return {};
+  }
+  if (ctx->False()) {
+    last = "0";
+    return {};
+  }
+  visitCondition(ctx->condition());
+  return {};
+}
+
+std::any EmitVisitor::visitExpr(xlangParser::ExprContext *ctx) {
+  OPERATOR(Plus, visitExpr, expr(), visitTerm, term(), "add");
+  OPERATOR(Minus, visitExpr, expr(), visitTerm, term(), "sub");
+  OPERATOR(BitAnd, visitExpr, expr(), visitTerm, term(), "and");
+  OPERATOR(BitOr, visitExpr, expr(), visitTerm, term(), "or");
+  OPERATOR(BitXor, visitExpr, expr(), visitTerm, term(), "xor");
+  OPERATOR(ShiftLeft, visitExpr, expr(), visitTerm, term(), "shl");
+  OPERATOR(ShiftRight, visitExpr, expr(), visitTerm, term(), "shr");
   visitTerm(ctx->term());
   return {};
 }
@@ -126,6 +153,18 @@ std::any EmitVisitor::visitTerm(xlangParser::TermContext *ctx) {
 }
 
 std::any EmitVisitor::visitFactor(xlangParser::FactorContext *ctx) {
+  if (ctx->Minus()) {
+    visitFactor(ctx->factor());
+    std::string f = last;
+    output << "  " << tmp() << " = w neg " << f << std::endl;
+    return {};
+  }
+  if (ctx->BitNot()) {
+    visitFactor(ctx->factor());
+    std::string f = last;
+    output << "  " << tmp() << " = w xor -1, " << f << std::endl;
+    return {};
+  }
   if (auto integer = ctx->Integer()) {
     last = integer->getSymbol()->getText();
     return {};
@@ -150,11 +189,7 @@ std::any EmitVisitor::visitFactor(xlangParser::FactorContext *ctx) {
     }
     return {};
   }
-  if (auto sum = ctx->sum()) {
-    visitSum(sum);
-    return {};
-  }
-  // unreachable
+  visitExpr(ctx->expr());
   return {};
 }
 
diff --git a/bootstrap/emit.hh b/bootstrap/emit.hh
index 7f1a3dc..e86c9c0 100644
--- a/bootstrap/emit.hh
+++ b/bootstrap/emit.hh
@@ -21,8 +21,9 @@ class EmitVisitor : public xlangBaseVisitor {
   std::any visitFile(xlangParser::FileContext *ctx) override;
   std::any visitFunction(xlangParser::FunctionContext *ctx) override;
   std::any visitStatement(xlangParser::StatementContext *ctx) override;
+  std::any visitCondition(xlangParser::ConditionContext *ctx) override;
+  std::any visitBoolean(xlangParser::BooleanContext *ctx) override;
   std::any visitExpr(xlangParser::ExprContext *ctx) override;
-  std::any visitSum(xlangParser::SumContext *ctx) override;
   std::any visitTerm(xlangParser::TermContext *ctx) override;
   std::any visitFactor(xlangParser::FactorContext *ctx) override;
 };
diff --git a/bootstrap/xlang.g4 b/bootstrap/xlang.g4
index 69a6f2f..6b23f6c 100644
--- a/bootstrap/xlang.g4
+++ b/bootstrap/xlang.g4
@@ -5,24 +5,32 @@ function  : Identifier LeftParen argumentList? RightParen block;
 argumentList  : Identifier (Comma Identifier)*;
 block : LeftBrace statement* RightBrace;
 statement : Identifier Assign expr Semicolon
-          | If expr block (Else block)?
-          | While expr block
+          | If condition block (Else block)?
+          | While condition block
           | Return expr Semicolon
           | Print expr Semicolon
           ;
-expr  : sum ((Less|LessEqual|Greater|GreaterEqual|Equal|NotEqual) sum)
-      | sum
+condition : condition (And|Or|Xor) boolean
+          | boolean
+          ;
+boolean : Not boolean
+        | expr (Less|LessEqual|Greater|GreaterEqual|Equal|NotEqual) expr
+        | True
+        | False
+        | LeftParen condition RightParen
+        ;
+expr  : expr (Plus|Minus|BitAnd|BitOr|BitXor|ShiftLeft|ShiftRight) term
+      | term
       ;
-sum : sum ((Plus|Minus) term)
-    | term
-    ;
-term  : term ((Mul|Div) factor)
+term  : term (Mul|Div) factor
       | factor
       ;
-factor  : Integer
+factor  : Minus factor
+        | BitNot factor
+        | Integer
         | Identifier
         | Identifier LeftParen exprList? RightParen
-        | LeftParen sum RightParen
+        | LeftParen expr RightParen
         ;
 exprList  : expr (Comma expr)*;
 
@@ -31,6 +39,12 @@ Else  : 'else';
 While : 'while';
 Return  : 'return';
 Print : 'print';
+And : 'and';
+Or  : 'or';
+Xor : 'xor';
+Not : 'not';
+True  : 'true';
+False : 'false';
 
 LeftParen : '(';
 RightParen  : ')';
@@ -45,6 +59,12 @@ Equal : '==';
 NotEqual  : '!=';
 Plus  : '+';
 Minus : '-';
+BitAnd  : '&';
+BitOr : '|';
+BitXor  : '^';
+ShiftLeft : '<<';
+ShiftRight  : '>>';
+BitNot  : '~';
 Mul : '*';
 Div : '/';
 Comma : ',';