diff --git a/acinclude.m4 b/acinclude.m4
index 49490a3047f..63f6b761e82 100644
--- a/acinclude.m4
+++ b/acinclude.m4
@@ -16,8 +16,7 @@ dnl
 dnl PHP_BUILD_THREAD_SAFE
 dnl
 AC_DEFUN(PHP_BUILD_THREAD_SAFE,[
-  enable_thread_safety=yes
-  passthru="$passthru --enable-thread-safety"
+  PHP_THREAD_SAFETY=yes
 ])
 
 dnl
diff --git a/configure.in b/configure.in
index 4a8067210fc..154c8454c7f 100644
--- a/configure.in
+++ b/configure.in
@@ -571,7 +571,15 @@ AC_ARG_ENABLE(dmalloc,
 ])
 AC_MSG_RESULT($DMALLOC_RESULT)
 
-dnl ## This is the default server API.
+AC_MSG_CHECKING(whether to enable experimental ZTS mode)
+AC_ARG_ENABLE(experimental-zts,
+[  --enable-experimental-zts   This will most likely break your build.],[
+  PHP_EXPERIMENTAL_ZTS=$enableval
+],[
+  PHP_EXPERIMENTAL_ZTS=no
+])
+AC_MSG_RESULT($PHP_EXPERIMENTAL_ZTS)
+
 PHP_SAPI=cgi
 PHP_BUILD_PROGRAM
 dnl paths to the targets relative to the build directory
@@ -591,19 +599,23 @@ esyscmd(./scripts/config-stubs ext)
 
 PHP_OUTPUT(sapi/$PHP_SAPI/Makefile)
 
-RESULT=no
 AC_MSG_CHECKING(whether to enable versioning)
 AC_ARG_ENABLE(versioning,
 [  --enable-versioning     Export only required symbols.
-                          See INSTALL for more information],
-[
-  test -z "$PHP_SYM_FILE" && PHP_SYM_FILE="$abs_srcdir/sapi/$PHP_SAPI/php.sym"
-  if test "$enableval" = "yes" && test -f "$PHP_SYM_FILE"; then
-    EXTRA_LDFLAGS="-export-symbols $PHP_SYM_FILE"
-    RESULT="yes"
-  fi
+                          See INSTALL for more information],[
+  PHP_VERSIONING=$enableval
+],[
+  PHP_VERSIONING=no
 ])
-AC_MSG_RESULT($RESULT)
+AC_MSG_RESULT($PHP_VERSIONING)
+
+if test "$PHP_VERSIONING" = "yes"; then
+  test -z "$PHP_SYM_FILE" && PHP_SYM_FILE="$abs_srcdir/sapi/$PHP_SAPI/php.sym"
+  if test -f "$PHP_SYM_FILE"; then
+    EXTRA_LDFLAGS="-export-symbols $PHP_SYM_FILE"
+  fi
+fi
+  
 
 divert(4)
 
@@ -639,22 +651,26 @@ PHP_REGEX
 dnl If we are using gcc and the user has not specified CFLAGS, add -O2.
 test -n "$auto_cflags" && test -n "$GCC" && CFLAGS="$CFLAGS -O2"
 
-AC_MSG_CHECKING(whether to build PHP thread-safe)
+
+
 
 CPPFLAGS="$CPPFLAGS -D_POSIX_PTHREAD_SEMANTICS"
 export CPPFLAGS
 
-if test "$enable_thread_safety" = "yes"; then
+if test "$PHP_THREAD_SAFETY" = "yes" || test "$PHP_EXPERIMENTAL_ZTS" = "yes"; then
+  passthru="$passthru --enable-thread-safety"
   TSRM_LIB='TSRM/libtsrm.la'
   TSRM_DIR=TSRM
   AC_DEFINE(ZTS)
   CPPFLAGS="$CPPFLAGS -D_REENTRANT"
   INCLUDES="$INCLUDES -I\$(top_builddir)/TSRM -I\$(top_srcdir)/TSRM"
-else 
-  enable_thread_safety=no
+  PHP_THREAD_SAFETY=yes
+else
+  PHP_THREAD_SAFETY=no
 fi
 
-AC_MSG_RESULT($enable_thread_safety)
+AC_MSG_CHECKING(whether to build PHP thread-safe)
+AC_MSG_RESULT($PHP_THREAD_SAFETY)
 
 AC_SUBST(TSRM_DIR)
 AC_SUBST(TSRM_LIB)