diff --git a/Changes.md b/Changes.md
index 384e7b0e..d0cd76ca 100644
--- a/Changes.md
+++ b/Changes.md
@@ -1,7 +1,10 @@
-## 1.7.2
+## 1.8.0
 
 * `PACKAGE_VERSION` is now a private compile definition when building
   with CMake. Pull request by bsergean. GitHub #308.
+* The feature test macro `_POSIX_C_SOURCE` is no longer set by
+  `maxminddb.h`. As discussed in GitHub #318, this should be set by
+  applications rather than by libraries.
 
 ## 1.7.1 - 2022-09-30
 
diff --git a/NOTICE b/NOTICE
index 7a695dee..dba215ea 100644
--- a/NOTICE
+++ b/NOTICE
@@ -1,4 +1,4 @@
-Copyright 2013-2022 MaxMind, Inc.
+Copyright 2013-2023 MaxMind, Inc.
 
 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
diff --git a/README.md b/README.md
index 2a4df66a..0a4949b9 100644
--- a/README.md
+++ b/README.md
@@ -110,6 +110,11 @@ Or with [MacPorts](https://ports.macports.org/port/libmaxminddb):
 
     $ sudo port install libmaxminddb
 
+# Requirements
+
+libmaxminddb requires a minimum of POSIX.1-2001 support. If not specified
+at compilation time, it defaults to requesting POSIX.1-2008 support.
+
 # Bug Reports
 
 Please report bugs by filing an issue with our GitHub issue tracker at
@@ -121,7 +126,7 @@ Use `make safedist` to check the resulting tarball.
 
 # Copyright and License
 
-Copyright 2013-2022 MaxMind, Inc.
+Copyright 2013-2023 MaxMind, Inc.
 
 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
diff --git a/bin/mmdblookup.c b/bin/mmdblookup.c
index 1989c57b..3652cd51 100644
--- a/bin/mmdblookup.c
+++ b/bin/mmdblookup.c
@@ -1,3 +1,7 @@
+#ifndef _POSIX_C_SOURCE
+#define _POSIX_C_SOURCE 200809L
+#endif
+
 #ifdef HAVE_CONFIG_H
 #include <config.h>
 #endif
diff --git a/doc/libmaxminddb.md b/doc/libmaxminddb.md
index 431d8054..48ac06a0 100644
--- a/doc/libmaxminddb.md
+++ b/doc/libmaxminddb.md
@@ -851,6 +851,11 @@ int main(int argc, char **argv)
 }
 ```
 
+# REQUIREMENTS
+
+libmaxminddb requires a minimum of POSIX.1-2001 support. If not specified
+at compilation time, it defaults to requesting POSIX.1-2008 support.
+
 # THREAD SAFETY
 
 This library is thread safe when compiled and linked with a thread-safe
@@ -878,7 +883,7 @@ Rolsky (drolsky@maxmind.com).
 
 # COPYRIGHT AND LICENSE
 
-Copyright 2013-2022 MaxMind, Inc.
+Copyright 2013-2023 MaxMind, Inc.
 
 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
diff --git a/doc/mmdblookup.md b/doc/mmdblookup.md
index 6278d11a..47946310 100644
--- a/doc/mmdblookup.md
+++ b/doc/mmdblookup.md
@@ -84,7 +84,7 @@ Rolsky (drolsky@maxmind.com).
 
 # COPYRIGHT AND LICENSE
 
-Copyright 2013-2022 MaxMind, Inc.
+Copyright 2013-2023 MaxMind, Inc.
 
 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
diff --git a/include/maxminddb.h b/include/maxminddb.h
index 028aa214..980abf99 100644
--- a/include/maxminddb.h
+++ b/include/maxminddb.h
@@ -5,18 +5,6 @@ extern "C" {
 #ifndef MAXMINDDB_H
 #define MAXMINDDB_H
 
-/* Request POSIX.1-2008. However, we want to remain compatible with
- * POSIX.1-2001 (since we have been historically and see no reason to drop
- * compatibility). By requesting POSIX.1-2008, we can conditionally use
- * features provided by that standard if the implementation provides it. We can
- * check for what the implementation provides by checking the _POSIX_VERSION
- * macro after including unistd.h. If a feature is in POSIX.1-2008 but not
- * POSIX.1-2001, check that macro before using the feature (or check for the
- * feature directly if possible). */
-#ifndef _POSIX_C_SOURCE
-#define _POSIX_C_SOURCE 200809L
-#endif
-
 #include "maxminddb_config.h"
 #include <stdarg.h>
 #include <stdbool.h>
diff --git a/src/data-pool.c b/src/data-pool.c
index 7b3c2a59..7d47ddff 100644
--- a/src/data-pool.c
+++ b/src/data-pool.c
@@ -1,3 +1,7 @@
+#ifndef _POSIX_C_SOURCE
+#define _POSIX_C_SOURCE 200809L
+#endif
+
 #include "data-pool.h"
 #include "maxminddb.h"
 
diff --git a/src/maxminddb.c b/src/maxminddb.c
index 7da1d340..c965c2a3 100644
--- a/src/maxminddb.c
+++ b/src/maxminddb.c
@@ -1,3 +1,7 @@
+#ifndef _POSIX_C_SOURCE
+#define _POSIX_C_SOURCE 200809L
+#endif
+
 #if HAVE_CONFIG_H
 #include <config.h>
 #endif
diff --git a/t/dump_t.c b/t/dump_t.c
index dae32ef8..2c817d03 100644
--- a/t/dump_t.c
+++ b/t/dump_t.c
@@ -1,4 +1,5 @@
 #define _XOPEN_SOURCE 700
+
 #include "maxminddb_test_helper.h"
 
 #ifdef HAVE_OPEN_MEMSTREAM
diff --git a/t/maxminddb_test_helper.c b/t/maxminddb_test_helper.c
index 7272c151..545cdc0c 100644
--- a/t/maxminddb_test_helper.c
+++ b/t/maxminddb_test_helper.c
@@ -1,14 +1,14 @@
+#include "maxminddb_test_helper.h"
+
 #if HAVE_CONFIG_H
 #include <config.h>
 #endif
 
-#define _POSIX_C_SOURCE 200112L
 #include <assert.h>
 #include <stdarg.h>
 #include <sys/types.h>
 
 #include "maxminddb.h"
-#include "maxminddb_test_helper.h"
 
 #ifdef _WIN32
 #include <io.h>
diff --git a/t/maxminddb_test_helper.h b/t/maxminddb_test_helper.h
index a782daa1..b037f955 100644
--- a/t/maxminddb_test_helper.h
+++ b/t/maxminddb_test_helper.h
@@ -1,6 +1,8 @@
-/* Some test files may require something newer */
-#if !defined(_GNU_SOURCE) && !defined(_POSIX_C_SOURCE)
-#define _POSIX_C_SOURCE 200112L
+// The spec says this should be set prior to including any headers, but since
+// this is test code, it should be fine to set it here. Setting it here avoids
+// setting it in every test program.
+#ifndef _POSIX_C_SOURCE
+#define _POSIX_C_SOURCE 200809L
 #endif
 
 #if HAVE_CONFIG_H