diff --git a/modules/desktop_capture/BUILD.gn b/modules/desktop_capture/BUILD.gn
index 7c07c9e3b2..54b11032fa 100644
--- a/modules/desktop_capture/BUILD.gn
+++ b/modules/desktop_capture/BUILD.gn
@@ -126,8 +126,6 @@ if (rtc_include_tests) {
       "screen_drawer.cc",
       "screen_drawer.h",
       "screen_drawer_linux.cc",
-      "screen_drawer_lock_posix.cc",
-      "screen_drawer_lock_posix.h",
       "screen_drawer_mac.cc",
       "screen_drawer_win.cc",
     ]
@@ -138,6 +136,13 @@ if (rtc_include_tests) {
       "../../rtc_base:rtc_base_approved",
       "../../system_wrappers",
     ]
+
+    if (is_posix || is_fuchsia) {
+      sources += [
+        "screen_drawer_lock_posix.cc",
+        "screen_drawer_lock_posix.h",
+      ]
+    }
   }
 
   source_set("desktop_capture_mock") {
diff --git a/system_wrappers/BUILD.gn b/system_wrappers/BUILD.gn
index d24b16ba6d..af778fd90c 100644
--- a/system_wrappers/BUILD.gn
+++ b/system_wrappers/BUILD.gn
@@ -25,8 +25,6 @@ rtc_static_library("system_wrappers") {
     "source/cpu_features.cc",
     "source/cpu_info.cc",
     "source/event.cc",
-    "source/event_timer_posix.cc",
-    "source/event_timer_posix.h",
     "source/event_timer_win.cc",
     "source/event_timer_win.h",
     "source/rtp_to_ntp_estimator.cc",
@@ -48,6 +46,13 @@ rtc_static_library("system_wrappers") {
     "../rtc_base/synchronization:rw_lock_wrapper",
   ]
 
+  if (is_posix || is_fuchsia) {
+    sources += [
+      "source/event_timer_posix.cc",
+      "source/event_timer_posix.h",
+    ]
+  }
+
   if (is_android) {
     defines += [ "WEBRTC_THREAD_RR" ]
 
@@ -208,7 +213,6 @@ if (rtc_include_tests) {
     testonly = true
     sources = [
       "source/clock_unittest.cc",
-      "source/event_timer_posix_unittest.cc",
       "source/metrics_default_unittest.cc",
       "source/metrics_unittest.cc",
       "source/ntp_time_unittest.cc",
@@ -216,6 +220,12 @@ if (rtc_include_tests) {
     ]
     configs += [ "//build/config/compiler:no_size_t_to_int_warning" ]
 
+    if (is_posix || is_fuchsia) {
+      sources += [
+        "source/event_timer_posix_unittest.cc",
+      ]
+    }
+
     if (!build_with_chromium && is_clang) {
       # Suppress warnings from the Chromium Clang plugin (bugs.webrtc.org/163).
       suppressed_configs += [ "//build/config/clang:find_bad_constructs" ]