diff --git a/Makefile.am b/Makefile.am
index 66d92ae8..40e2b269 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -126,7 +126,7 @@ EXTRA_DIST = test/fixtures/empty_file \
 
 TESTS = test/run-tests
 check_PROGRAMS = test/run-tests
-test_run_tests_CFLAGS = -Wno-long-long
+test_run_tests_CFLAGS =
 test_run_tests_LDFLAGS =
 test_run_tests_SOURCES = test/blackhole-server.c \
                          test/dns-server.c \
@@ -276,7 +276,7 @@ test_run_tests_CFLAGS += -D_ALL_SOURCE -D_XOPEN_SOURCE=500 -D_LINUX_SOURCE_COMPA
 endif
 
 if SUNOS
-test_run_tests_CFLAGS += -D__EXTENSIONS__ -D_XOPEN_SOURCE=500
+test_run_tests_CFLAGS += -D__EXTENSIONS__ -D_XOPEN_SOURCE=600
 endif
 
 
@@ -345,7 +345,7 @@ endif
 
 if SUNOS
 include_HEADERS += include/uv-sunos.h
-libuv_la_CFLAGS += -D__EXTENSIONS__ -D_XOPEN_SOURCE=500
+libuv_la_CFLAGS += -D__EXTENSIONS__ -D_XOPEN_SOURCE=600
 libuv_la_SOURCES += src/unix/sunos.c
 endif
 
diff --git a/Makefile.mingw b/Makefile.mingw
index f7349b44..21702d82 100644
--- a/Makefile.mingw
+++ b/Makefile.mingw
@@ -17,6 +17,7 @@ CC ?= gcc
 CFLAGS += -Wall \
           -Wextra \
           -Wno-unused-parameter \
+          -std=gnu99 \
           -Iinclude \
           -Isrc \
           -Isrc/win \
diff --git a/configure.ac b/configure.ac
index 4a106bec..06df36b5 100644
--- a/configure.ac
+++ b/configure.ac
@@ -26,7 +26,7 @@ AC_PROG_CC
 AM_PROG_CC_C_O
 CC_FLAG_VISIBILITY #[-fvisibility=hidden]
 CC_CHECK_CFLAGS_APPEND([-g])
-CC_CHECK_CFLAGS_APPEND([-std=gnu89])
+CC_CHECK_CFLAGS_APPEND([-std=gnu99])
 CC_CHECK_CFLAGS_APPEND([-pedantic])
 CC_CHECK_CFLAGS_APPEND([-Wall])
 CC_CHECK_CFLAGS_APPEND([-Wextra])
diff --git a/src/unix/internal.h b/src/unix/internal.h
index 6ad29a9f..710595b9 100644
--- a/src/unix/internal.h
+++ b/src/unix/internal.h
@@ -30,10 +30,6 @@
 #include <fcntl.h>  /* O_CLOEXEC, may be */
 #include <stdio.h>
 
-#if defined(__STRICT_ANSI__)
-# define inline __inline
-#endif
-
 #if defined(__linux__)
 # include "linux-syscalls.h"
 #endif /* __linux__ */
diff --git a/test/task.h b/test/task.h
index 0260b04a..2a618ca4 100644
--- a/test/task.h
+++ b/test/task.h
@@ -34,11 +34,6 @@
 # include <sys/resource.h>  /* setrlimit() */
 #endif
 
-#ifdef __clang__
-# pragma clang diagnostic ignored "-Wvariadic-macros"
-# pragma clang diagnostic ignored "-Wc99-extensions"
-#endif
-
 #define TEST_PORT 9123
 #define TEST_PORT_2 9124
 
diff --git a/uv.gyp b/uv.gyp
index 12a7ebde..863e0175 100644
--- a/uv.gyp
+++ b/uv.gyp
@@ -19,7 +19,7 @@
     'xcode_settings': {
       'GCC_SYMBOLS_PRIVATE_EXTERN': 'YES',  # -fvisibility=hidden
       'WARNING_CFLAGS': [ '-Wall', '-Wextra', '-Wno-unused-parameter' ],
-      'OTHER_CFLAGS': [ '-g', '--std=gnu89', '-pedantic' ],
+      'OTHER_CFLAGS': [ '-g', '--std=gnu99', '-pedantic' ],
     }
   },
 
@@ -119,7 +119,7 @@
           'cflags': [
             '-fvisibility=hidden',
             '-g',
-            '--std=gnu89',
+            '--std=gnu99',
             '-pedantic',
             '-Wall',
             '-Wextra',
@@ -226,7 +226,7 @@
           'sources': [ 'src/unix/sunos.c' ],
           'defines': [
             '__EXTENSIONS__',
-            '_XOPEN_SOURCE=500',
+            '_XOPEN_SOURCE=600',
           ],
           'link_settings': {
             'libraries': [
@@ -425,7 +425,6 @@
           'libraries': [ '-lws2_32' ]
         }, { # POSIX
           'defines': [ '_GNU_SOURCE' ],
-          'cflags': [ '-Wno-long-long' ],
           'sources': [
             'test/runner-unix.c',
             'test/runner-unix.h',