diff --git a/libc/async_safe/Android.bp b/libc/async_safe/Android.bp
index a54d3b0..6ae1c42 100644
--- a/libc/async_safe/Android.bp
+++ b/libc/async_safe/Android.bp
@@ -12,7 +12,19 @@
     recovery_available: true,
 
     include_dirs: ["bionic/libc"],
-    header_libs: ["libc_headers"],
+    header_libs: ["libc_headers", "liblog_headers"],
 
     export_include_dirs: ["include"],
+    export_header_lib_headers: ["liblog_headers"],
+    stl: "none",
+}
+
+cc_library_headers {
+    name: "libasync_safe_headers",
+    recovery_available: true,
+
+    export_include_dirs: ["include"],
+
+    system_shared_libs: [],
+    stl: "none",
 }
diff --git a/libc/async_safe/include/async_safe/CHECK.h b/libc/async_safe/include/async_safe/CHECK.h
new file mode 100644
index 0000000..bec89a3
--- /dev/null
+++ b/libc/async_safe/include/async_safe/CHECK.h
@@ -0,0 +1,47 @@
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#pragma once
+
+#include <sys/cdefs.h>
+
+#include <async_safe/log.h>
+
+__BEGIN_DECLS
+
+// TODO: replace this with something more like <android-base/logging.h>'s family of macros.
+
+#define CHECK(predicate) \
+  do { \
+    if (!(predicate)) { \
+      async_safe_fatal("%s:%d: %s CHECK '" #predicate "' failed", \
+          __FILE__, __LINE__, __FUNCTION__); \
+    } \
+  } while(0)
+
+__END_DECLS
diff --git a/libc/async_safe/include/async_safe/log.h b/libc/async_safe/include/async_safe/log.h
index df68062..0e02ea7 100644
--- a/libc/async_safe/include/async_safe/log.h
+++ b/libc/async_safe/include/async_safe/log.h
@@ -34,36 +34,14 @@
 #include <stdint.h>
 #include <stdlib.h>
 
+// This file is an alternative to <android/log.h>, but reuses
+// `android_LogPriority` and should not have conflicting identifiers.
+#include <android/log.h>
+
 // These functions do not allocate memory to send data to the log.
 
 __BEGIN_DECLS
 
-enum {
-  ANDROID_LOG_UNKNOWN = 0,
-  ANDROID_LOG_DEFAULT,    /* only for SetMinPriority() */
-
-  ANDROID_LOG_VERBOSE,
-  ANDROID_LOG_DEBUG,
-  ANDROID_LOG_INFO,
-  ANDROID_LOG_WARN,
-  ANDROID_LOG_ERROR,
-  ANDROID_LOG_FATAL,
-
-  ANDROID_LOG_SILENT,     /* only for SetMinPriority(); must be last */
-};
-
-enum {
-  LOG_ID_MIN = 0,
-
-  LOG_ID_MAIN = 0,
-  LOG_ID_RADIO = 1,
-  LOG_ID_EVENTS = 2,
-  LOG_ID_SYSTEM = 3,
-  LOG_ID_CRASH = 4,
-
-  LOG_ID_MAX
-};
-
 // Formats a message to the log (priority 'fatal'), then aborts.
 // Implemented as a macro so that async_safe_fatal isn't on the stack when we crash:
 // we appear to go straight from the caller to abort, saving an uninteresting stack
@@ -91,16 +69,8 @@
 
 int async_safe_format_fd(int fd, const char* format , ...) __printflike(2, 3);
 int async_safe_format_fd_va_list(int fd, const char* format, va_list args);
-int async_safe_format_log(int pri, const char* tag, const char* fmt, ...) __printflike(3, 4);
-int async_safe_format_log_va_list(int pri, const char* tag, const char* fmt, va_list ap);
-int async_safe_write_log(int pri, const char* tag, const char* msg);
-
-#define CHECK(predicate) \
-  do { \
-    if (!(predicate)) { \
-      async_safe_fatal("%s:%d: %s CHECK '" #predicate "' failed", \
-          __FILE__, __LINE__, __FUNCTION__); \
-    } \
-  } while(0)
+int async_safe_format_log(int priority, const char* tag, const char* fmt, ...) __printflike(3, 4);
+int async_safe_format_log_va_list(int priority, const char* tag, const char* fmt, va_list ap);
+int async_safe_write_log(int priority, const char* tag, const char* msg);
 
 __END_DECLS