diff --git a/lib/std/process/Child.zig b/lib/std/process/Child.zig
index da8d803d60..7d56e92be6 100644
--- a/lib/std/process/Child.zig
+++ b/lib/std/process/Child.zig
@@ -122,7 +122,7 @@ pub const ResourceUsageStatistics = struct {
     /// if available.
     pub inline fn getMaxRss(rus: ResourceUsageStatistics) ?usize {
         switch (native_os) {
-            .linux => {
+            .freebsd, .illumos, .linux, .serenity => {
                 if (rus.rusage) |ru| {
                     return @as(usize, @intCast(ru.maxrss)) * 1024;
                 } else {
@@ -149,7 +149,18 @@ pub const ResourceUsageStatistics = struct {
     }
 
     const rusage_init = switch (native_os) {
-        .linux, .driverkit, .ios, .maccatalyst, .macos, .tvos, .visionos, .watchos => @as(?posix.rusage, null),
+        .freebsd,
+        .illumos,
+        .linux,
+        .serenity,
+        .driverkit,
+        .ios,
+        .maccatalyst,
+        .macos,
+        .tvos,
+        .visionos,
+        .watchos,
+        => @as(?posix.rusage, null),
         .windows => @as(?windows.VM_COUNTERS, null),
         else => {},
     };
@@ -486,7 +497,18 @@ fn waitUnwrappedPosix(self: *ChildProcess) void {
     const res: posix.WaitPidResult = res: {
         if (self.request_resource_usage_statistics) {
             switch (native_os) {
-                .linux, .driverkit, .ios, .maccatalyst, .macos, .tvos, .visionos, .watchos => {
+                .freebsd,
+                .illumos,
+                .linux,
+                .serenity,
+                .driverkit,
+                .ios,
+                .maccatalyst,
+                .macos,
+                .tvos,
+                .visionos,
+                .watchos,
+                => {
                     var ru: posix.rusage = undefined;
                     const res = posix.wait4(self.id, 0, &ru);
                     self.resource_usage_statistics.rusage = ru;