diff --git a/lang/include/ivy/lang/lex.h b/lang/include/ivy/lang/lex.h
index 60224d4..531a33f 100644
--- a/lang/include/ivy/lang/lex.h
+++ b/lang/include/ivy/lang/lex.h
@@ -45,6 +45,8 @@ enum ivy_keyword {
 	IVY_KW_ELSE,
 	IVY_KW_WHILE,
 	IVY_KW_FOR,
+	IVY_KW_CONTINUE,
+	IVY_KW_BREAK,
 	IVY_KW_MATCH,
 	IVY_KW_UNLESS,
 	IVY_KW_IN,
@@ -52,7 +54,10 @@ enum ivy_keyword {
 	IVY_KW_GET,
 	IVY_KW_SET,
 	IVY_KW_END,
-	IVY_KW_VAR,
+	IVY_KW_GLOBAL,
+	IVY_KW_TRUE,
+	IVY_KW_FALSE,
+	IVY_KW_NULL,
 	__IVY_KW_INDEX_LIMIT,
 };
 
diff --git a/lang/lex.c b/lang/lex.c
index 718a509..6745392 100644
--- a/lang/lex.c
+++ b/lang/lex.c
@@ -42,6 +42,8 @@ static struct lex_token_def keywords[] = {
 	LEX_TOKEN_DEF(IVY_KW_NOT, "not"),
 	LEX_TOKEN_DEF(IVY_KW_WHILE, "while"),
 	LEX_TOKEN_DEF(IVY_KW_FOR, "for"),
+	LEX_TOKEN_DEF(IVY_KW_CONTINUE, "continue"),
+	LEX_TOKEN_DEF(IVY_KW_BREAK, "break"),
 	LEX_TOKEN_DEF(IVY_KW_MATCH, "match"),
 	LEX_TOKEN_DEF(IVY_KW_UNLESS, "unless"),
 	LEX_TOKEN_DEF(IVY_KW_IN, "in"),
@@ -49,7 +51,10 @@ static struct lex_token_def keywords[] = {
 	LEX_TOKEN_DEF(IVY_KW_GET, "get"),
 	LEX_TOKEN_DEF(IVY_KW_SET, "set"),
 	LEX_TOKEN_DEF(IVY_KW_END, "end"),
-	LEX_TOKEN_DEF(IVY_KW_VAR, "var"),
+	LEX_TOKEN_DEF(IVY_KW_GLOBAL, "global"),
+	LEX_TOKEN_DEF(IVY_KW_TRUE, "true"),
+	LEX_TOKEN_DEF(IVY_KW_FALSE, "false"),
+	LEX_TOKEN_DEF(IVY_KW_NULL, "null"),
 };
 static const size_t nr_keywords = sizeof keywords / sizeof keywords[0];
 
@@ -376,11 +381,11 @@ static int peek(struct ivy_lexer *lex)
 	}
 
 	if (status != IVY_OK) {
-		return status;
+		return -status;
 	}
 
 	if (lex->lex_linebuf_len == 0) {
-		return IVY_ERR_EOF;
+		return -IVY_ERR_EOF;
 	}
 
 	int c = lex->lex_linebuf[lex->lex_linebuf_ptr];
@@ -396,15 +401,15 @@ static int peek_next(struct ivy_lexer *lex)
 	}
 
 	if (status != IVY_OK) {
-		return status;
+		return -status;
 	}
 
 	if (lex->lex_linebuf_len == 0) {
-		return IVY_ERR_EOF;
+		return -IVY_ERR_EOF;
 	}
 
 	if (lex->lex_linebuf_ptr + 1 >= lex->lex_linebuf_len) {
-		return IVY_ERR_EOF;
+		return -IVY_ERR_EOF;
 	}
 
 	int c = lex->lex_linebuf[lex->lex_linebuf_ptr + 1];
@@ -420,11 +425,11 @@ static int advance(struct ivy_lexer *lex)
 	}
 
 	if (status != IVY_OK) {
-		return status;
+		return -status;
 	}
 
 	if (lex->lex_linebuf_len == 0) {
-		return IVY_ERR_EOF;
+		return -IVY_ERR_EOF;
 	}
 
 	int c = lex->lex_linebuf[lex->lex_linebuf_ptr++];
@@ -623,12 +628,12 @@ static enum ivy_status read_line_comment(struct ivy_lexer *lex)
 	while (true) {
 		int c = advance(lex);
 
-		if (c == IVY_ERR_EOF || c == '\n') {
+		if (c == -IVY_ERR_EOF || c == '\n') {
 			break;
 		}
 
 		if (c < 0) {
-			return c;
+			return -c;
 		}
 	}
 
@@ -643,7 +648,7 @@ static enum ivy_status read_block_comment(struct ivy_lexer *lex)
 	while (depth > 0) {
 		int c = peek(lex);
 		if (c < 0) {
-			return c;
+			return -c;
 		}
 
 		if (!buf[0]) {
@@ -717,12 +722,12 @@ static enum ivy_status read_atom(struct ivy_lexer *lex)
 	while (true) {
 		int c = peek(lex);
 
-		if (c == IVY_ERR_EOF) {
+		if (c == -IVY_ERR_EOF) {
 			break;
 		}
 
 		if (c < 0) {
-			return c;
+			return -c;
 		}
 
 		if (!isalnum(c) && c != ':' && c != '_') {
@@ -756,6 +761,9 @@ static enum ivy_status read_string_content(struct ivy_lexer *lex)
 
 	while (true) {
 		c = peek(lex);
+		if (c < 0) {
+			break;
+		}
 
 		if (state->s_type == STATE_FSTRING && (c == '\'' || c == '{')) {
 			break;
@@ -794,6 +802,9 @@ static enum ivy_status read_symbol(struct ivy_lexer *lex)
 
 	while (true) {
 		int c = peek(lex);
+		if (c < 0) {
+			break;
+		}
 
 		struct ivy_lexer_symbol_node *next = get_symbol_node(node, c);
 		if (!next) {
@@ -853,12 +864,12 @@ static enum ivy_status read_number(struct ivy_lexer *lex)
 
 	while (true) {
 		int c = peek(lex);
-		if (c == IVY_ERR_EOF) {
+		if (c == -IVY_ERR_EOF) {
 			break;
 		}
 
 		if (c < 0) {
-			return c;
+			return -c;
 		}
 
 		if (c == '_') {
@@ -1036,7 +1047,7 @@ static enum ivy_status pump_tokens(struct ivy_lexer *lex)
 	int c = peek(lex);
 
 	if (c < 0) {
-		return c;
+		return -c;
 	}
 
 	if (state->s_type == STATE_STRING && c != '"') {
@@ -1067,7 +1078,7 @@ static enum ivy_status pump_tokens(struct ivy_lexer *lex)
 		}
 
 		if (c < 0) {
-			return c;
+			return -c;
 		}
 
 		return push_linefeed(lex);
@@ -1227,6 +1238,8 @@ const char *ivy_keyword_to_string(enum ivy_keyword keyword)
 		ENUM_STR(IVY_KW_ELSE);
 		ENUM_STR(IVY_KW_WHILE);
 		ENUM_STR(IVY_KW_FOR);
+		ENUM_STR(IVY_KW_CONTINUE);
+		ENUM_STR(IVY_KW_BREAK);
 		ENUM_STR(IVY_KW_MATCH);
 		ENUM_STR(IVY_KW_UNLESS);
 		ENUM_STR(IVY_KW_IN);
@@ -1234,7 +1247,10 @@ const char *ivy_keyword_to_string(enum ivy_keyword keyword)
 		ENUM_STR(IVY_KW_GET);
 		ENUM_STR(IVY_KW_SET);
 		ENUM_STR(IVY_KW_END);
-		ENUM_STR(IVY_KW_VAR);
+		ENUM_STR(IVY_KW_GLOBAL);
+		ENUM_STR(IVY_KW_TRUE);
+		ENUM_STR(IVY_KW_FALSE);
+		ENUM_STR(IVY_KW_NULL);
 	default:
 		return "";
 	}