diff --git a/fastboot/Android.bp b/fastboot/Android.bp
index 1a91d1e..a1f1c17 100644
--- a/fastboot/Android.bp
+++ b/fastboot/Android.bp
@@ -271,6 +271,12 @@
 
     generated_headers: ["platform_tools_version"],
 
+    tidy_flags: [
+        // DO NOT add quotes around header-filter flag regex argument,
+        // because build/soong will add quotes around the whole flag.
+        "-header-filter=(system/core/fastboot/|development/host/windows/usb/api/)",
+    ],
+
     target: {
         windows: {
             srcs: ["usb_windows.cpp"],
diff --git a/libutils/include/utils/SystemClock.h b/libutils/include/utils/SystemClock.h
index 892104c..3c59297 100644
--- a/libutils/include/utils/SystemClock.h
+++ b/libutils/include/utils/SystemClock.h
@@ -20,11 +20,18 @@
 #include <stdint.h>
 #include <sys/types.h>
 
+// See https://developer.android.com/reference/android/os/SystemClock
+// to learn more about Android's timekeeping facilities.
+
 namespace android {
 
+// Returns milliseconds since boot, not counting time spent in deep sleep.
 int64_t uptimeMillis();
+// Returns nanoseconds since boot, not counting time spent in deep sleep.
 int64_t uptimeNanos();
+// Returns milliseconds since boot, including time spent in sleep.
 int64_t elapsedRealtime();
+// Returns nanoseconds since boot, including time spent in sleep.
 int64_t elapsedRealtimeNano();
 
 }  // namespace android
diff --git a/trusty/coverage/Android.bp b/trusty/coverage/Android.bp
index fb30604..c71d599 100644
--- a/trusty/coverage/Android.bp
+++ b/trusty/coverage/Android.bp
@@ -25,14 +25,11 @@
     export_include_dirs: [
         "include",
     ],
-    static_libs: [
-        "libtrusty",
-    ],
-
     shared_libs: [
         "libbase",
         "liblog",
         "libdmabufheap",
+        "libtrusty",
     ],
 }
 
diff --git a/trusty/fuzz/Android.bp b/trusty/fuzz/Android.bp
index c8c9fe9..99156f4 100644
--- a/trusty/fuzz/Android.bp
+++ b/trusty/fuzz/Android.bp
@@ -19,6 +19,7 @@
 cc_defaults {
     name: "trusty_fuzzer_defaults",
     shared_libs: [
+        "libtrusty",
         "libtrusty_coverage",
         "libtrusty_fuzz_utils",
         "libbase",
@@ -43,11 +44,11 @@
     export_include_dirs: ["include"],
     static_libs: [
         "libFuzzer",
-        "libtrusty",
     ],
     shared_libs: [
         "libtrusty_coverage",
         "libbase",
         "liblog",
+        "libtrusty",
     ],
 }