diff --git a/acinclude.m4 b/acinclude.m4
index aec18cfa506..221d8303376 100644
--- a/acinclude.m4
+++ b/acinclude.m4
@@ -16,7 +16,7 @@ dnl
 dnl PHP_BUILD_THREAD_SAFE
 dnl
 AC_DEFUN(PHP_BUILD_THREAD_SAFE,[
-  PHP_THREAD_SAFETY=yes
+  enable_experimental_zts=yes
 ])
 
 dnl
diff --git a/configure.in b/configure.in
index 3207f2b8282..de278c26293 100644
--- a/configure.in
+++ b/configure.in
@@ -693,8 +693,7 @@ CPPFLAGS="$CPPFLAGS -D_POSIX_PTHREAD_SEMANTICS -D_REENTRANT"
 LIBZEND_BASIC_CHECKS
 LIBZEND_OTHER_CHECKS
 
-
-if test "$PHP_THREAD_SAFETY" = "yes" || test "$ZEND_EXPERIMENTAL_ZTS" = "yes"; then
+if test "$ZEND_EXPERIMENTAL_ZTS" = "yes"; then
   TSRM_LIB='TSRM/libtsrm.la'
   TSRM_DIR=TSRM
   AC_DEFINE(ZTS)