diff --git a/lib/std/fs/path.zig b/lib/std/fs/path.zig
index d5ba5fe909..f07d884c68 100644
--- a/lib/std/fs/path.zig
+++ b/lib/std/fs/path.zig
@@ -5,6 +5,7 @@ const assert = debug.assert;
 const testing = std.testing;
 const mem = std.mem;
 const fmt = std.fmt;
+const ascii = std.ascii;
 const Allocator = mem.Allocator;
 const math = std.math;
 const windows = std.os.windows;
@@ -423,7 +424,7 @@ fn networkShareServersEql(ns1: []const u8, ns2: []const u8) bool {
     var it2 = mem.tokenize(u8, ns2, &[_]u8{sep2});
 
     // TODO ASCII is wrong, we actually need full unicode support to compare paths.
-    return asciiEqlIgnoreCase(it1.next().?, it2.next().?);
+    return ascii.eqlIgnoreCase(it1.next().?, it2.next().?);
 }
 
 fn compareDiskDesignators(kind: WindowsPath.Kind, p1: []const u8, p2: []const u8) bool {
@@ -434,7 +435,7 @@ fn compareDiskDesignators(kind: WindowsPath.Kind, p1: []const u8, p2: []const u8
             return true;
         },
         WindowsPath.Kind.Drive => {
-            return asciiUpper(p1[0]) == asciiUpper(p2[0]);
+            return ascii.toUpper(p1[0]) == ascii.toUpper(p2[0]);
         },
         WindowsPath.Kind.NetworkShare => {
             const sep1 = p1[0];
@@ -444,29 +445,11 @@ fn compareDiskDesignators(kind: WindowsPath.Kind, p1: []const u8, p2: []const u8
             var it2 = mem.tokenize(u8, p2, &[_]u8{sep2});
 
             // TODO ASCII is wrong, we actually need full unicode support to compare paths.
-            return asciiEqlIgnoreCase(it1.next().?, it2.next().?) and asciiEqlIgnoreCase(it1.next().?, it2.next().?);
+            return ascii.eqlIgnoreCase(it1.next().?, it2.next().?) and ascii.eqlIgnoreCase(it1.next().?, it2.next().?);
         },
     }
 }
 
-fn asciiUpper(byte: u8) u8 {
-    return switch (byte) {
-        'a'...'z' => 'A' + (byte - 'a'),
-        else => byte,
-    };
-}
-
-fn asciiEqlIgnoreCase(s1: []const u8, s2: []const u8) bool {
-    if (s1.len != s2.len)
-        return false;
-    var i: usize = 0;
-    while (i < s1.len) : (i += 1) {
-        if (asciiUpper(s1[i]) != asciiUpper(s2[i]))
-            return false;
-    }
-    return true;
-}
-
 /// On Windows, this calls `resolveWindows` and on POSIX it calls `resolvePosix`.
 pub fn resolve(allocator: Allocator, paths: []const []const u8) ![]u8 {
     if (native_os == .windows) {
@@ -506,7 +489,7 @@ pub fn resolveWindows(allocator: Allocator, paths: []const []const u8) ![]u8 {
         }
         switch (parsed.kind) {
             WindowsPath.Kind.Drive => {
-                result_drive_buf[0] = asciiUpper(parsed.disk_designator[0]);
+                result_drive_buf[0] = ascii.toUpper(parsed.disk_designator[0]);
                 result_disk_designator = result_drive_buf[0..];
                 have_drive_kind = WindowsPath.Kind.Drive;
             },
@@ -590,7 +573,7 @@ pub fn resolveWindows(allocator: Allocator, paths: []const []const u8) ![]u8 {
                 result_index += parsed_cwd.disk_designator.len;
                 result_disk_designator = result[0..parsed_cwd.disk_designator.len];
                 if (parsed_cwd.kind == WindowsPath.Kind.Drive) {
-                    result[0] = asciiUpper(result[0]);
+                    result[0] = ascii.toUpper(result[0]);
                 }
                 have_drive_kind = parsed_cwd.kind;
             },
@@ -608,7 +591,7 @@ pub fn resolveWindows(allocator: Allocator, paths: []const []const u8) ![]u8 {
         const parsed_cwd = windowsParsePath(result[0..result_index]);
         result_disk_designator = parsed_cwd.disk_designator;
         if (parsed_cwd.kind == WindowsPath.Kind.Drive) {
-            result[0] = asciiUpper(result[0]);
+            result[0] = ascii.toUpper(result[0]);
             // Remove the trailing slash if present, eg. if the cwd is a root
             // directory.
             if (cwd.len > 0 and cwd[cwd.len - 1] == sep_windows) {
@@ -741,7 +724,7 @@ test "resolve" {
     defer testing.allocator.free(cwd);
     if (native_os == .windows) {
         if (windowsParsePath(cwd).kind == WindowsPath.Kind.Drive) {
-            cwd[0] = asciiUpper(cwd[0]);
+            cwd[0] = ascii.toUpper(cwd[0]);
         }
         try testResolveWindows(&[_][]const u8{"."}, cwd);
     } else {
@@ -768,7 +751,7 @@ test "resolveWindows" {
             });
             defer testing.allocator.free(expected);
             if (parsed_cwd.kind == WindowsPath.Kind.Drive) {
-                expected[0] = asciiUpper(parsed_cwd.disk_designator[0]);
+                expected[0] = ascii.toUpper(parsed_cwd.disk_designator[0]);
             }
             try testResolveWindows(&[_][]const u8{ "/usr/local", "lib\\zig\\std\\array_list.zig" }, expected);
         }
@@ -779,7 +762,7 @@ test "resolveWindows" {
             });
             defer testing.allocator.free(expected);
             if (parsed_cwd.kind == WindowsPath.Kind.Drive) {
-                expected[0] = asciiUpper(parsed_cwd.disk_designator[0]);
+                expected[0] = ascii.toUpper(parsed_cwd.disk_designator[0]);
             }
             try testResolveWindows(&[_][]const u8{ "usr/local", "lib\\zig" }, expected);
         }
@@ -1110,7 +1093,7 @@ pub fn relativeWindows(allocator: Allocator, from: []const u8, to: []const u8) !
                 break :x !networkShareServersEql(parsed_to.disk_designator, parsed_from.disk_designator);
             },
             WindowsPath.Kind.Drive => {
-                break :x asciiUpper(parsed_from.disk_designator[0]) != asciiUpper(parsed_to.disk_designator[0]);
+                break :x ascii.toUpper(parsed_from.disk_designator[0]) != ascii.toUpper(parsed_to.disk_designator[0]);
             },
             else => unreachable,
         }
@@ -1128,7 +1111,7 @@ pub fn relativeWindows(allocator: Allocator, from: []const u8, to: []const u8) !
         const to_rest = to_it.rest();
         if (to_it.next()) |to_component| {
             // TODO ASCII is wrong, we actually need full unicode support to compare paths.
-            if (asciiEqlIgnoreCase(from_component, to_component))
+            if (ascii.eqlIgnoreCase(from_component, to_component))
                 continue;
         }
         var up_count: usize = 1;