diff --git a/ares/configure.ac b/ares/configure.ac
index f1f52a5bcfa29166c973e38202be5f2436f56c93..4c719cf75e8227f9ce2a607abda2b4ffa5f6fc83 100644
--- a/ares/configure.ac
+++ b/ares/configure.ac
@@ -382,33 +382,6 @@ AC_HELP_STRING([--enable-libgcc],[use libgcc when linking]),
)
-dnl Default is to try the thread-safe versions of a few functions
-OPT_THREAD=on
-
-AC_ARG_ENABLE(thread,dnl
-AC_HELP_STRING([--disable-thread],[don't look for thread-safe functions])
-AC_HELP_STRING([--enable-thread],[look for thread-safe functions]),
-[ case "$enableval" in
- no)
- OPT_THREAD=off
- AC_MSG_WARN(c-ares will not get built using thread-safe functions)
- ;;
- *)
- ;;
- esac
-]
-)
-
-if test X"$OPT_THREAD" = Xoff
-then
- AC_DEFINE(DISABLED_THREADSAFE, 1,
- [Set to explicitly specify we don't want to use thread-safe functions])
-fi
-
-dnl for recent AIX versions, we skip all the thread-safe checks above since
-dnl they claim a thread-safe libc using the standard API. But there are
-dnl some functions still not thread-safe. Check for these!
-
dnl Let's hope this split URL remains working:
dnl http://publibn.boulder.ibm.com/doc_link/en_US/a_doc_lib/aixprggd/ \
dnl genprogc/thread_quick_ref.htm
diff --git a/configure.ac b/configure.ac
index b23bc78a0117ab0baf37f0205eeac85824435951..5f605443d43f01ea8cc5b3b81f47f3dcf83fe8ba 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1827,51 +1827,6 @@ case "$LIBIDN" in
;;
esac
-dnl Default is to try the thread-safe versions of a few functions
-OPT_THREAD=on
-
-AC_ARG_ENABLE(thread,dnl
-AC_HELP_STRING([--disable-thread],[don't look for thread-safe functions])
-AC_HELP_STRING([--enable-thread],[look for thread-safe functions]),
-[ case "$enableval" in
- no)
- OPT_THREAD=off
- AC_MSG_WARN(libcurl will not get built using thread-safe functions)
- ;;
- *)
- ;;
- esac
-]
-)
-
-if test X"$OPT_THREAD" = Xoff
-then
- AC_DEFINE(DISABLED_THREADSAFE, 1,
- [Set to explicitly specify we don't want to use thread-safe functions])
-else
- dnl if test "$ipv6" != "yes"; then
- dnl dig around for gethostbyname_r()
- dnl the old gethostbyname_r check was done here
-
- dnl dig around for gethostbyaddr_r()
- dnl the old gethostbyaddr_r check was here BUT COMMENTED OUT
- dnl fi
-
- dnl poke around for inet_ntoa_r()
- dnl the old inet_ntoa_r check was done here
-
- dnl is there a localtime_r()
- dnl the old localtime_r check was done here
-
- dnl is there a strerror_r()
- dnl the old strerror_r check was done here
-
- checkfor_gmtime_r="yes"
-fi
-
-dnl for recent AIX versions, we skip all the thread-safe checks above since
-dnl they claim a thread-safe libc using the standard API. But there are
-dnl some functions still not thread-safe. Check for these!
dnl Let's hope this split URL remains working:
dnl http://publibn.boulder.ibm.com/doc_link/en_US/a_doc_lib/aixprggd/ \
diff --git a/lib/config-os400.h b/lib/config-os400.h
index 371cbea281db6445a9cc7644a755dec00d5fe009..7a303fdbb7ae086bd0ddb97ee871010ebc16968e 100644
--- a/lib/config-os400.h
+++ b/lib/config-os400.h
@@ -54,9 +54,6 @@
/* Define this to your Entropy Gathering Daemon socket pathname */
#undef EGD_SOCKET
-/* Set to explicitly specify we don't want to use thread-safe functions */
-#undef DISABLED_THREADSAFE
-
/* Define to 1 if you have the alarm function. */
#define HAVE_ALARM 1
diff --git a/lib/config-riscos.h b/lib/config-riscos.h
index 912bb8aa765b860680ca41fc94178364f33e82dd..a5b6850f5ed8e99c9b486e3d83d57fb8241f863a 100644
--- a/lib/config-riscos.h
+++ b/lib/config-riscos.h
@@ -50,9 +50,6 @@
/* Define this to your Entropy Gathering Daemon socket pathname */
#undef EGD_SOCKET
-/* Set to explicitly specify we don't want to use thread-safe functions */
-#define DISABLED_THREADSAFE
-
/* Define if you want to enable IPv6 support */
#undef ENABLE_IPV6
diff --git a/lib/config-symbian.h b/lib/config-symbian.h
index d3bf209248047b638c01c35b583909536d5d3638..207d9040e4bc460445f194d66681f496c467e980 100644
--- a/lib/config-symbian.h
+++ b/lib/config-symbian.h
@@ -57,9 +57,6 @@
/* when not building a shared library */
/* #undef CURL_STATICLIB */
-/* Set to explicitly specify we don't want to use thread-safe functions */
-/* #undef DISABLED_THREADSAFE */
-
/* your Entropy Gathering Daemon socket pathname */
/* #undef EGD_SOCKET */
diff --git a/lib/config-tpf.h b/lib/config-tpf.h
index fd995bf4ca8514909ad61c6bc9364bf0d69b23e8..efbd9b4299dc9f730ad40b3d3f5f927b62a84187 100644
--- a/lib/config-tpf.h
+++ b/lib/config-tpf.h
@@ -47,9 +47,6 @@
/* when not building a shared library */
/* #undef CURL_STATICLIB */
-/* Set to explicitly specify we don't want to use thread-safe functions */
-/* #undef DISABLED_THREADSAFE */
-
/* lber dynamic library file */
/* #undef DL_LBER_FILE */
diff --git a/lib/config-vxworks.h b/lib/config-vxworks.h
index 26b8074d5962eead1ae202cb340208c21cd712f7..2d386aff067926b3d0a93d06531f8405496486c1 100644
--- a/lib/config-vxworks.h
+++ b/lib/config-vxworks.h
@@ -68,9 +68,6 @@
/* when not building a shared library */
/* #undef CURL_STATICLIB */
-/* Set to explicitly specify we don't want to use thread-safe functions */
-/* #undef DISABLED_THREADSAFE */
-
/* your Entropy Gathering Daemon socket pathname */
/* #undef EGD_SOCKET */
diff --git a/src/config-riscos.h b/src/config-riscos.h
index b397e0dd818432a2c3f130a5c36da474ba3d2e39..222ff635939be5401fea99f3b02870a7436a4365 100644
--- a/src/config-riscos.h
+++ b/src/config-riscos.h
@@ -53,9 +53,6 @@
/* Define this to your Entropy Gathering Daemon socket pathname */
#undef EGD_SOCKET
-/* Set to explicitly specify we don't want to use thread-safe functions */
-#define DISABLED_THREADSAFE
-
/* Define if you want to enable IPv6 support */
#undef ENABLE_IPV6