diff --git a/lib/compiler_rt/int_from_float.zig b/lib/compiler_rt/int_from_float.zig
index 0c2c73bb42..83de968a2e 100644
--- a/lib/compiler_rt/int_from_float.zig
+++ b/lib/compiler_rt/int_from_float.zig
@@ -74,7 +74,7 @@ pub inline fn bigIntFromFloat(comptime signedness: std.builtin.Signedness, resul
     const parts = math.frexp(a);
     const significand_bits_adjusted_to_handle_smin = @as(i32, significand_bits) +
         @intFromBool(signedness == .signed and parts.exponent == 32 * result.len);
-    const exponent = @max(parts.exponent - significand_bits_adjusted_to_handle_smin, 0);
+    const exponent: usize = @intCast(@max(parts.exponent - significand_bits_adjusted_to_handle_smin, 0));
     const int: I = @intFromFloat(switch (exponent) {
         0 => a,
         else => math.ldexp(parts.significand, significand_bits_adjusted_to_handle_smin),
diff --git a/lib/std/Io/Writer.zig b/lib/std/Io/Writer.zig
index 7ad466d5cb..a525a028d7 100644
--- a/lib/std/Io/Writer.zig
+++ b/lib/std/Io/Writer.zig
@@ -604,7 +604,7 @@ pub fn print(w: *Writer, comptime fmt: []const u8, args: anytype) Error!void {
         @compileError("32 arguments max are supported per format call");
     }
 
-    @setEvalBranchQuota(fmt.len * 1000);
+    @setEvalBranchQuota(@as(comptime_int, fmt.len) * 1000); // NOTE: We're upcasting as 16-bit usize overflows.
     comptime var arg_state: std.fmt.ArgState = .{ .args_len = fields_info.len };
     comptime var i = 0;
     comptime var literal: []const u8 = "";
diff --git a/lib/std/os/windows.zig b/lib/std/os/windows.zig
index 2e18e8ec16..27b40fcd60 100644
--- a/lib/std/os/windows.zig
+++ b/lib/std/os/windows.zig
@@ -4634,25 +4634,28 @@ pub const TEB = extern struct {
 };
 
 comptime {
-    // Offsets taken from WinDbg info and Geoff Chappell[1] (RIP)
-    // [1]: https://www.geoffchappell.com/studies/windows/km/ntoskrnl/inc/api/pebteb/teb/index.htm
-    assert(@offsetOf(TEB, "NtTib") == 0x00);
-    if (@sizeOf(usize) == 4) {
-        assert(@offsetOf(TEB, "EnvironmentPointer") == 0x1C);
-        assert(@offsetOf(TEB, "ClientId") == 0x20);
-        assert(@offsetOf(TEB, "ActiveRpcHandle") == 0x28);
-        assert(@offsetOf(TEB, "ThreadLocalStoragePointer") == 0x2C);
-        assert(@offsetOf(TEB, "ProcessEnvironmentBlock") == 0x30);
-        assert(@offsetOf(TEB, "LastErrorValue") == 0x34);
-        assert(@offsetOf(TEB, "TlsSlots") == 0xe10);
-    } else if (@sizeOf(usize) == 8) {
-        assert(@offsetOf(TEB, "EnvironmentPointer") == 0x38);
-        assert(@offsetOf(TEB, "ClientId") == 0x40);
-        assert(@offsetOf(TEB, "ActiveRpcHandle") == 0x50);
-        assert(@offsetOf(TEB, "ThreadLocalStoragePointer") == 0x58);
-        assert(@offsetOf(TEB, "ProcessEnvironmentBlock") == 0x60);
-        assert(@offsetOf(TEB, "LastErrorValue") == 0x68);
-        assert(@offsetOf(TEB, "TlsSlots") == 0x1480);
+    // XXX: Without this check we cannot use `std.Io.Writer` on 16-bit platforms. `std.fmt.bufPrint` will hit the unreachable in `PEB.GdiHandleBuffer` without this guard.
+    if (builtin.os.tag == .windows) {
+        // Offsets taken from WinDbg info and Geoff Chappell[1] (RIP)
+        // [1]: https://www.geoffchappell.com/studies/windows/km/ntoskrnl/inc/api/pebteb/teb/index.htm
+        assert(@offsetOf(TEB, "NtTib") == 0x00);
+        if (@sizeOf(usize) == 4) {
+            assert(@offsetOf(TEB, "EnvironmentPointer") == 0x1C);
+            assert(@offsetOf(TEB, "ClientId") == 0x20);
+            assert(@offsetOf(TEB, "ActiveRpcHandle") == 0x28);
+            assert(@offsetOf(TEB, "ThreadLocalStoragePointer") == 0x2C);
+            assert(@offsetOf(TEB, "ProcessEnvironmentBlock") == 0x30);
+            assert(@offsetOf(TEB, "LastErrorValue") == 0x34);
+            assert(@offsetOf(TEB, "TlsSlots") == 0xe10);
+        } else if (@sizeOf(usize) == 8) {
+            assert(@offsetOf(TEB, "EnvironmentPointer") == 0x38);
+            assert(@offsetOf(TEB, "ClientId") == 0x40);
+            assert(@offsetOf(TEB, "ActiveRpcHandle") == 0x50);
+            assert(@offsetOf(TEB, "ThreadLocalStoragePointer") == 0x58);
+            assert(@offsetOf(TEB, "ProcessEnvironmentBlock") == 0x60);
+            assert(@offsetOf(TEB, "LastErrorValue") == 0x68);
+            assert(@offsetOf(TEB, "TlsSlots") == 0x1480);
+        }
     }
 }