diff --git a/lib/std/Build/Step/ConfigHeader.zig b/lib/std/Build/Step/ConfigHeader.zig
index f474c38ff0..72d5e99e3a 100644
--- a/lib/std/Build/Step/ConfigHeader.zig
+++ b/lib/std/Build/Step/ConfigHeader.zig
@@ -131,7 +131,7 @@ fn putValue(config_header: *ConfigHeader, field_name: []const u8, comptime T: ty
         .comptime_int => {
             try config_header.values.put(field_name, .{ .int = v });
         },
-        .enum_literal => {
+        .@"enum", .enum_literal => {
             try config_header.values.put(field_name, .{ .ident = @tagName(v) });
         },
         .optional => {
@@ -264,8 +264,11 @@ fn render_autoconf(
     values: std.StringArrayHashMap(Value),
     src_path: []const u8,
 ) !void {
-    var values_copy = try values.clone();
-    defer values_copy.deinit();
+    const build = step.owner;
+    const allocator = build.allocator;
+
+    var is_used: std.DynamicBitSetUnmanaged = try .initEmpty(allocator, values.count());
+    defer is_used.deinit(allocator);
 
     var any_errors = false;
     var line_index: u32 = 0;
@@ -283,19 +286,21 @@ fn render_autoconf(
             try output.appendSlice("\n");
             continue;
         }
-        const name = it.rest();
-        const kv = values_copy.fetchSwapRemove(name) orelse {
+        const name = it.next().?;
+        const index = values.getIndex(name) orelse {
             try step.addError("{s}:{d}: error: unspecified config header value: '{s}'", .{
                 src_path, line_index + 1, name,
             });
             any_errors = true;
             continue;
         };
-        try renderValueC(output, name, kv.value);
+        is_used.set(index);
+        try renderValueC(output, name, values.values()[index]);
     }
 
-    for (values_copy.keys()) |name| {
-        try step.addError("{s}: error: config header value unused: '{s}'", .{ src_path, name });
+    var unused_value_it = is_used.iterator(.{ .kind = .unset });
+    while (unused_value_it.next()) |index| {
+        try step.addError("{s}: error: config header value unused: '{s}'", .{ src_path, values.keys()[index] });
         any_errors = true;
     }
 
diff --git a/test/standalone/build.zig.zon b/test/standalone/build.zig.zon
index 9863e7cc6d..db1c7125a7 100644
--- a/test/standalone/build.zig.zon
+++ b/test/standalone/build.zig.zon
@@ -186,6 +186,9 @@
         .omit_cfi = .{
             .path = "omit_cfi",
         },
+        .config_header = .{
+            .path = "config_header",
+        },
     },
     .paths = .{
         "build.zig",
diff --git a/test/standalone/config_header/build.zig b/test/standalone/config_header/build.zig
new file mode 100644
index 0000000000..423e9d3823
--- /dev/null
+++ b/test/standalone/config_header/build.zig
@@ -0,0 +1,28 @@
+const std = @import("std");
+
+pub fn build(b: *std.Build) void {
+    const config_header = b.addConfigHeader(
+        .{ .style = .{ .autoconf = b.path("config.h.in") } },
+        .{
+            .SOME_NO = null,
+            .SOME_TRUE = true,
+            .SOME_FALSE = false,
+            .SOME_ZERO = 0,
+            .SOME_ONE = 1,
+            .SOME_TEN = 10,
+            .SOME_ENUM = @as(enum { foo, bar }, .foo),
+            .SOME_ENUM_LITERAL = .@"test",
+            .SOME_STRING = "test",
+
+            .PREFIX_SPACE = null,
+            .PREFIX_TAB = null,
+            .POSTFIX_SPACE = null,
+            .POSTFIX_TAB = null,
+        },
+    );
+
+    const check_config_header = b.addCheckFile(config_header.getOutput(), .{ .expected_exact = @embedFile("config.h") });
+
+    const test_step = b.step("test", "Test it");
+    test_step.dependOn(&check_config_header.step);
+}
diff --git a/test/standalone/config_header/config.h b/test/standalone/config_header/config.h
new file mode 100644
index 0000000000..22b5fb5697
--- /dev/null
+++ b/test/standalone/config_header/config.h
@@ -0,0 +1,23 @@
+/* This file was generated by ConfigHeader using the Zig Build System. */
+/* Some Comment */
+
+int foo();
+
+/* #undef SOME_NO */
+#define SOME_TRUE 1
+#define SOME_FALSE 0
+#define SOME_ZERO 0
+#define SOME_ONE 1
+#define SOME_TEN 10
+#define SOME_ENUM foo
+#define SOME_ENUM_LITERAL test
+#define SOME_STRING "test"
+
+// Used twice
+#define SOME_TRUE 1
+
+/* #undef PREFIX_SPACE */
+/* #undef PREFIX_TAB */
+/* #undef POSTFIX_SPACE */
+/* #undef POSTFIX_TAB */
+
diff --git a/test/standalone/config_header/config.h.in b/test/standalone/config_header/config.h.in
new file mode 100644
index 0000000000..c1b8fe7236
--- /dev/null
+++ b/test/standalone/config_header/config.h.in
@@ -0,0 +1,21 @@
+/* Some Comment */
+
+int foo();
+
+#undef SOME_NO
+#undef SOME_TRUE
+#undef SOME_FALSE
+#undef SOME_ZERO
+#undef SOME_ONE
+#undef SOME_TEN
+#undef SOME_ENUM
+#undef SOME_ENUM_LITERAL
+#undef SOME_STRING
+
+// Used twice
+#undef SOME_TRUE
+
+#undef PREFIX_SPACE
+#undef	PREFIX_TAB
+#undef POSTFIX_SPACE 
+#undef POSTFIX_TAB