diff --git a/hblang/src/lexer.rs b/hblang/src/lexer.rs
index b103860..8f36d69 100644
--- a/hblang/src/lexer.rs
+++ b/hblang/src/lexer.rs
@@ -292,6 +292,18 @@ impl<'a> Lexer<'a> {
 
             let kind = match c {
                 ..=b' ' => continue,
+                b'0' if self.advance_if(b'x') => {
+                    while let Some(b'0'..=b'9') = self.peek() {
+                        self.advance();
+                    }
+                    T::Number
+                }
+                b'0' if self.advance_if(b'b') => {
+                    while let Some(b'0'..=b'9') = self.peek() {
+                        self.advance();
+                    }
+                    T::Number
+                }
                 b'0'..=b'9' => {
                     while let Some(b'0'..=b'9') = self.peek() {
                         self.advance();
diff --git a/hblang/src/parser.rs b/hblang/src/parser.rs
index 59fe5f8..6908f3b 100644
--- a/hblang/src/parser.rs
+++ b/hblang/src/parser.rs
@@ -391,9 +391,18 @@ impl<'a, 'b> Parser<'a, 'b> {
             },
             T::Number => E::Number {
                 pos: token.start,
-                value: match self.lexer.slice(token.range()).parse() {
-                    Ok(value) => value,
-                    Err(e) => self.report(format_args!("invalid number: {e}")),
+                value: {
+                    let slice = self.lexer.slice(token.range());
+                    let (slice, radix) = match &slice.get(0..2) {
+                        Some("0x") => (slice.trim_start_matches("0x"), 16),
+                        Some("0b") => (slice.trim_start_matches("0b"), 16),
+                        Some("0o") => (slice.trim_start_matches("0o"), 16),
+                        _ => (slice, 10),
+                    };
+                    match u64::from_str_radix(slice, radix) {
+                        Ok(value) => value,
+                        Err(e) => self.report(format_args!("invalid number: {e}")),
+                    }
                 },
             },
             T::LParen => {