diff --git a/app/src/main/java/com/annimon/hotarufx/lexer/HotaruLexer.java b/app/src/main/java/com/annimon/hotarufx/lexer/HotaruLexer.java
index 939b9b6..2519f5c 100644
--- a/app/src/main/java/com/annimon/hotarufx/lexer/HotaruLexer.java
+++ b/app/src/main/java/com/annimon/hotarufx/lexer/HotaruLexer.java
@@ -34,6 +34,13 @@ public class HotaruLexer extends Lexer {
         OPERATORS.put("@", HotaruTokenId.AT);
     }
 
+    private static final Map<String, HotaruTokenId> KEYWORDS;
+    static {
+        KEYWORDS = new HashMap<>();
+        KEYWORDS.put("true", HotaruTokenId.TRUE);
+        KEYWORDS.put("false", HotaruTokenId.FALSE);
+    }
+
     public HotaruLexer(String input) {
         super(input);
     }
@@ -91,7 +98,7 @@ public class HotaruLexer extends Lexer {
         }
 
         val word = getBuffer().toString();
-        return addToken(HotaruTokenId.WORD, word);
+        return addToken(KEYWORDS.getOrDefault(word, HotaruTokenId.WORD));
     }
 
     private Token tokenizeText(char openChar) {
diff --git a/app/src/main/java/com/annimon/hotarufx/lexer/HotaruTokenId.java b/app/src/main/java/com/annimon/hotarufx/lexer/HotaruTokenId.java
index 264b397..e1f5bff 100644
--- a/app/src/main/java/com/annimon/hotarufx/lexer/HotaruTokenId.java
+++ b/app/src/main/java/com/annimon/hotarufx/lexer/HotaruTokenId.java
@@ -10,6 +10,9 @@ public enum HotaruTokenId {
     WORD(Category.IDENTIFIER),
     TEXT(Category.STRING),
 
+    TRUE(Category.KEYWORD),
+    FALSE(Category.KEYWORD),
+
     EQ(Category.OPERATOR),
     PLUS(Category.OPERATOR),
     MINUS(Category.OPERATOR),
@@ -31,7 +34,7 @@ public enum HotaruTokenId {
     EOF(Category.WHITESPACE);
 
     private enum Category {
-        NUMBER, IDENTIFIER, STRING, OPERATOR, COMMENT, WHITESPACE
+        NUMBER, IDENTIFIER, STRING, KEYWORD, OPERATOR, COMMENT, WHITESPACE
     }
 
     private final Category category;
diff --git a/app/src/main/java/com/annimon/hotarufx/parser/HotaruParser.java b/app/src/main/java/com/annimon/hotarufx/parser/HotaruParser.java
index 3d31295..75d59e0 100644
--- a/app/src/main/java/com/annimon/hotarufx/parser/HotaruParser.java
+++ b/app/src/main/java/com/annimon/hotarufx/parser/HotaruParser.java
@@ -3,6 +3,7 @@ package com.annimon.hotarufx.parser;
 import com.annimon.hotarufx.exceptions.ParseException;
 import com.annimon.hotarufx.lexer.HotaruTokenId;
 import com.annimon.hotarufx.lexer.Token;
+import com.annimon.hotarufx.lib.NumberValue;
 import com.annimon.hotarufx.parser.ast.*;
 import java.util.ArrayList;
 import java.util.HashMap;
@@ -219,6 +220,12 @@ public class HotaruParser extends Parser {
 
     private Node value() {
         val current = get(0);
+        if (match(HotaruTokenId.TRUE)) {
+            return new ValueNode(NumberValue.ONE);
+        }
+        if (match(HotaruTokenId.FALSE)) {
+            return new ValueNode(NumberValue.ZERO);
+        }
         if (match(HotaruTokenId.NUMBER)) {
             return new ValueNode(createNumber(current.getText(), 10));
         }
diff --git a/app/src/main/resources/main.hfx b/app/src/main/resources/main.hfx
index dd90345..fdb5df2 100644
--- a/app/src/main/resources/main.hfx
+++ b/app/src/main/resources/main.hfx
@@ -87,7 +87,7 @@ POLYLINE = polyline(points, {
 })
 
 LINE = line({
-  visible: 0,
+  visible: false,
   startX: -600
   startY: 300
   endX: 600
@@ -95,7 +95,7 @@ LINE = line({
   stroke: "#777",
   strokeDashOffset: 45
 })
-LINE@visible.add(100, 1)
+LINE@visible.add(100, true)
 LINE@strokeWidth.add(100, 0).add(140, 10)
 
 arcRadius = 200
diff --git a/app/src/test/java/com/annimon/hotarufx/parser/HotaruParserTest.java b/app/src/test/java/com/annimon/hotarufx/parser/HotaruParserTest.java
index 9170c00..c198d09 100644
--- a/app/src/test/java/com/annimon/hotarufx/parser/HotaruParserTest.java
+++ b/app/src/test/java/com/annimon/hotarufx/parser/HotaruParserTest.java
@@ -2,6 +2,7 @@ package com.annimon.hotarufx.parser;
 
 import com.annimon.hotarufx.exceptions.ParseException;
 import com.annimon.hotarufx.lexer.HotaruLexer;
+import com.annimon.hotarufx.lib.NumberValue;
 import com.annimon.hotarufx.parser.ast.AssignNode;
 import com.annimon.hotarufx.parser.ast.BlockNode;
 import com.annimon.hotarufx.parser.ast.FunctionNode;
@@ -9,6 +10,8 @@ import com.annimon.hotarufx.parser.ast.MapNode;
 import com.annimon.hotarufx.parser.ast.Node;
 import com.annimon.hotarufx.parser.ast.ValueNode;
 import com.annimon.hotarufx.parser.ast.VariableNode;
+import java.util.Arrays;
+import lombok.val;
 import org.junit.jupiter.api.Test;
 import static org.hamcrest.MatcherAssert.assertThat;
 import static org.hamcrest.Matchers.allOf;
@@ -59,6 +62,33 @@ class HotaruParserTest {
         ));
     }
 
+    @Test
+    void testParseTrueFalse() {
+        String input = "A = true\nB = false";
+        Node node = p(input);
+        assertThat(node, instanceOf(BlockNode.class));
+
+        val block = (BlockNode) node;
+        assertThat(block.statements.size(), is(2));
+
+        val expectedValues = Arrays.asList(
+                NumberValue.fromBoolean(true),
+                NumberValue.fromBoolean(false)
+        );
+        val it = expectedValues.iterator();
+
+        for (Node statement : block.statements) {
+            assertThat(statement, instanceOf(AssignNode.class));
+
+            val assignNode = (AssignNode) statement;
+            assertThat(assignNode.target, instanceOf(VariableNode.class));
+            assertThat(assignNode.value, instanceOf(ValueNode.class));
+
+            val value = ((ValueNode) assignNode.value).value;
+            assertThat(value, is(it.next()));
+        }
+    }
+
     @Test
     void testParseErrors() {
         assertThrows(ParseException.class, () -> p("A ="));