diff --git a/examples/curl.zr b/examples/curl.zr
index 6034ddf..2f7540f 100644
--- a/examples/curl.zr
+++ b/examples/curl.zr
@@ -3,7 +3,7 @@ func main[argc: i64, argv: ptr] : i64
         io.println("ERROR: url is missing")
         return 1
 
-    let url: str = mem.read64(argv + 8)
+    let url: str = mem.read64(argv + 8) as str
 
     if str.len(url) <= 7
         io.println("ERROR: invalid url (Did you forget \"http://\"?)")
@@ -36,7 +36,7 @@ func main[argc: i64, argv: ptr] : i64
     req = str.concat(req, " HTTP/1.0\r\nHost: ")
     req = str.concat(req, host)
     req = str.concat(req, "\r\nConnection: close\r\n\r\n")
-    net.send(s, req, str.len(req))
+    net.send(s, req as ptr, str.len(req))
     mem.free(req)
 
     let header_buf: str = mem.alloc(8192)
@@ -45,7 +45,7 @@ func main[argc: i64, argv: ptr] : i64
     let end_index: i64 = -1
 
     while !found && header_size < 8192
-        let n: i64 = net.read(s, header_buf + header_size, 8192 - header_size)
+        let n: i64 = net.read(s, header_buf as ptr + header_size, 8192 - header_size)
         if n <= 0
             break
         let current_size: i64 = header_size + n
@@ -59,7 +59,7 @@ func main[argc: i64, argv: ptr] : i64
         header_size = current_size
 
     if end_index < header_size
-        io.print_sized(header_buf + end_index, header_size - end_index)
+        io.print_sized(header_buf as ptr + end_index, header_size as i64 - end_index)
     mem.free(header_buf)
 
     let buffer: ptr = mem.alloc(4096)
diff --git a/examples/puzzles/aoc2025_03.zr b/examples/puzzles/aoc2025_03.zr
index 6054439..61cc246 100644
--- a/examples/puzzles/aoc2025_03.zr
+++ b/examples/puzzles/aoc2025_03.zr
@@ -25,7 +25,7 @@ func part2_rec[bank: str, start: i64, remaining: i64] : i64
     let len: i64 = str.len(bank)
 
     for i in (start)..(len-remaining+1)
-        let v: i64 = bank[i] - '0'
+        let v: i64 = (bank[i] - '0') as i64
         if v > largest
             largest = v
             largest_idx = i
diff --git a/examples/tcp_server.zr b/examples/tcp_server.zr
index de94fb7..a45250f 100644
--- a/examples/tcp_server.zr
+++ b/examples/tcp_server.zr
@@ -2,7 +2,7 @@ func main[] : i64
     let s: i64 = must(net.listen?(net.pack_addr(127, 0, 0, 1), 8000))
 
     io.println("Listening on port 8000...")
-    let resp: str = mem.alloc(60000)
+    let resp: ptr = mem.alloc(60000)
     while true
         let conn: i64 = net.accept(s)
         if conn < 0
diff --git a/examples/udp_server.zr b/examples/udp_server.zr
index 5f2f345..e784f5d 100644
--- a/examples/udp_server.zr
+++ b/examples/udp_server.zr
@@ -1,5 +1,5 @@
 func main[] : i64
-    let s: i64 = must(net.udp_listen?(net.pack_addr(127, 0, 0, 1), 8000))
+    let s: net.UDPSocket = must(net.udp_listen?(net.pack_addr(127, 0, 0, 1), 8000))
 
     io.println("Listening on port 8000...")
     while true
diff --git a/src/std/std.zr b/src/std/std.zr
index a1d7ce6..165eafe 100644
--- a/src/std/std.zr
+++ b/src/std/std.zr
@@ -289,18 +289,18 @@ func io._printf_impl[s: ptr, args: ptr] : void
             io.print_char(s[0])
         s = s + 1
 
-func io.print_sized[x: str, size: i64] : void
+func io.print_sized[x: ptr, size: i64] : void
     _builtin_syscall(SYS_write, 1, x, size)
 
 func io.print[x: str] : void
-    io.print_sized(x, str.len(x))
+    io.print_sized(x as ptr, str.len(x))
 
 func io.println[x: str] : void
     io.print(x)
     io.print("\n")
 
 func io.print_char[x: u8] : void
-    io.print_sized(^x as str, 1)
+    io.print_sized(^x, 1)
 
 func io.print_bool[x: bool] : void
     if x
@@ -860,7 +860,7 @@ func alg.count[arr: Array, item: any] : i64
             count = count + 1
     return count
 
-func alg.map[arr: Array, fn: ptr] : Array
+func alg.map[arr: Array, fn: fnptr] : Array
     let out: Array = array.new_with_size_zeroed(arr->size)
     for i in 0..arr->size
         array.set(out, i, fn(array.nth(arr, i)))
diff --git a/src/typechecker.rs b/src/typechecker.rs
index d044521..d772ffe 100644
--- a/src/typechecker.rs
+++ b/src/typechecker.rs
@@ -35,7 +35,6 @@ macro_rules! expect_types {
     };
 }
 
-// TODO: currently they are all just 64 bit values
 static BUILTIN_TYPES: [&str; 8] = ["void", "u8", "i64", "str", "bool", "ptr", "fnptr", "any"];
 
 pub struct Env {
@@ -245,7 +244,7 @@ impl TypeChecker {
                         Ok("i64".into())
                     }
                     TokenType::Bang => {
-                        expect_types!(right_type, ["bool", "i64", "ptr"], op.loc);
+                        expect_types!(right_type, ["bool", "i64", "ptr", "u8"], op.loc);
                         Ok("bool".into())
                     }
                     _ => unreachable!(),
@@ -371,10 +370,18 @@ impl TypeChecker {
                 expect_types!(self.typecheck_expr(env, index)?, ["i64", "u8"], bracket.loc);
                 Ok("u8".into())
             }
-            Expr::AddrOf { op, expr } => {
-                self.typecheck_expr(env, expr)?;
-                Ok("ptr".into())
-            }
+            Expr::AddrOf { op, expr } => match *expr.clone() {
+                Expr::Variable(name) => {
+                    if self.analyzer.borrow().functions.contains_key(&name.lexeme) {
+                        Ok("fnptr".into())
+                    } else {
+                        Ok("ptr".into())
+                    }
+                }
+                _ => {
+                    error!(&op.loc, "can only take address of variables and functions")
+                }
+            },
             Expr::New(struct_name) => Ok(struct_name.lexeme.clone()),
             Expr::MemberAccess { left, field } => {
                 let left_type = self.typecheck_expr(env, left)?;