diff --git a/configure.ac b/configure.ac
index ed03c46e7cb..5139702e2d4 100644
--- a/configure.ac
+++ b/configure.ac
@@ -105,8 +105,6 @@ extern "C++" {
 #endif
 #endif /* ifndef ZEND_ACCONFIG_H_NO_C_PROTOS */
 
-#undef PTHREADS
-
 #endif /* PHP_CONFIG_H */
 ])