diff --git a/core/os/stream.odin b/core/os/stream.odin
index 7d3749a32..1815262c7 100644
--- a/core/os/stream.odin
+++ b/core/os/stream.odin
@@ -20,8 +20,10 @@ _file_stream_vtable := &io.Stream_VTable{
 	},
 	impl_read_at = proc(s: io.Stream, p: []byte, offset: i64) -> (n: int, err: io.Error) {
 		fd := Handle(uintptr(s.stream_data));
-		os_err: Errno;
-		n, os_err = read_at(fd, p, offset);
+		when ODIN_OS == "windows" {
+			os_err: Errno;
+			n, os_err = read_at(fd, p, offset);
+		}
 		return;
 	},
 	impl_write = proc(s: io.Stream, p: []byte) -> (n: int, err: io.Error) {
@@ -32,13 +34,17 @@ _file_stream_vtable := &io.Stream_VTable{
 	},
 	impl_write_at = proc(s: io.Stream, p: []byte, offset: i64) -> (n: int, err: io.Error) {
 		fd := Handle(uintptr(s.stream_data));
-		os_err: Errno;
-		n, os_err = write_at(fd, p, offset);
+		when ODIN_OS == "windows" {
+			os_err: Errno;
+			n, os_err = write_at(fd, p, offset);
+			_ = os_err;
+		}
 		return;
 	},
 	impl_seek = proc(s: io.Stream, offset: i64, whence: io.Seek_From) -> (i64, io.Error) {
 		fd := Handle(uintptr(s.stream_data));
 		n, os_err := seek(fd, offset, int(whence));
+		_ = os_err;
 		return n, nil;
 	},
 	impl_size = proc(s: io.Stream) -> i64 {
diff --git a/core/text/scanner/scanner.odin b/core/text/scanner/scanner.odin
index dad9c6d95..bbd2090b6 100644
--- a/core/text/scanner/scanner.odin
+++ b/core/text/scanner/scanner.odin
@@ -262,13 +262,12 @@ scan_number :: proc(s: ^Scanner, ch: rune, seen_dot: bool) -> (rune, rune) {
 
 	if !seen_dot {
 		tok = Int;
-		ch0 := ch;
 		if ch == '0' {
 			ch = advance(s);
 
 			p := lower(ch);
 			if .Scan_C_Int_Prefixes in s.flags {
-				switch lower(ch) {
+				switch p {
 				case 'b':
 					ch = advance(s);
 					base, prefix = 2, 'b';
@@ -280,7 +279,7 @@ scan_number :: proc(s: ^Scanner, ch: rune, seen_dot: bool) -> (rune, rune) {
 					digsep = 1; // Leading zero
 				}
 			} else {
-				switch lower(ch) {
+				switch p {
 				case 'b':
 					ch = advance(s);
 					base, prefix = 2, 'b';