diff --git a/ext/hash/config.m4 b/ext/hash/config.m4
index 00075da06ff5..f87d00bf86e3 100644
--- a/ext/hash/config.m4
+++ b/ext/hash/config.m4
@@ -32,7 +32,6 @@ else
 fi
 
 PHP_ADD_BUILD_DIR(ext/hash/murmur, 1)
-PHP_HASH_CFLAGS="$PHP_HASH_CFLAGS -I@ext_srcdir@/xxhash"
 
 EXT_HASH_SOURCES="hash.c hash_md.c hash_sha.c hash_ripemd.c hash_haval.c \
   hash_tiger.c hash_gost.c hash_snefru.c hash_whirlpool.c hash_adler32.c \
@@ -42,7 +41,7 @@ EXT_HASH_HEADERS="php_hash.h php_hash_md.h php_hash_sha.h php_hash_ripemd.h \
   php_hash_haval.h php_hash_tiger.h php_hash_gost.h php_hash_snefru.h \
   php_hash_whirlpool.h php_hash_adler32.h php_hash_crc32.h \
   php_hash_fnv.h php_hash_joaat.h php_hash_sha3.h php_hash_murmur.h \
-  php_hash_xxhash.h"
+  php_hash_xxhash.h xxhash/xxhash.h"
 
 PHP_NEW_EXTENSION(hash, $EXT_HASH_SOURCES, 0,,$PHP_HASH_CFLAGS)
 PHP_INSTALL_HEADERS(ext/hash, $EXT_HASH_HEADERS)
diff --git a/ext/hash/config.w32 b/ext/hash/config.w32
index 61c8fcb35b75..b66f7c582e97 100644
--- a/ext/hash/config.w32
+++ b/ext/hash/config.w32
@@ -35,13 +35,9 @@ if (!CHECK_HEADER_ADD_INCLUDE('PMurHash.h', 'CFLAGS_HASH', hash_murmur_dir)) {
 }
 ADD_SOURCES(hash_murmur_dir, 'PMurHash.c PMurHash128.c', 'hash');
 
-var hash_xxhash_dir = 'ext/hash/xxhash';
-if (!CHECK_HEADER_ADD_INCLUDE('xxhash.h', 'CFLAGS_HASH', hash_xxhash_dir)) {
-	ERROR('Unable to locate xxhash headers');
-}
-
 PHP_INSTALL_HEADERS('ext/hash/',	'php_hash.h php_hash_md.h php_hash_sha.h ' +
 									'php_hash_ripemd.h php_hash_haval.h php_hash_tiger.h ' +
 									'php_hash_gost.h php_hash_snefru.h php_hash_whirlpool.h ' +
 									'php_hash_adler32.h php_hash_crc32.h php_hash_sha3.h ' +
-									'php_hash_murmur.h php_hash_xxhash.h');
+									'php_hash_murmur.h php_hash_xxhash.h php_hash_fnv.h ' +
+									'php_hash_joaat.h xxhash/xxhash.h');
diff --git a/ext/hash/php_hash_xxhash.h b/ext/hash/php_hash_xxhash.h
index a1e8840ce272..ed2e2e098737 100644
--- a/ext/hash/php_hash_xxhash.h
+++ b/ext/hash/php_hash_xxhash.h
@@ -17,8 +17,11 @@
 #ifndef PHP_HASH_XXHASH_H
 #define PHP_HASH_XXHASH_H
 
+/* Undefined, if xxhash namespace was already set elsewhere. */
+#undef XXH_NAMESPACE
+#define XXH_NAMESPACE PHP_NAMESPACE
 #define XXH_INLINE_ALL 1
-#include "xxhash.h"
+#include "xxhash/xxhash.h"
 
 typedef struct {
 	XXH32_state_t s;