diff --git a/bootstrap.sh b/bootstrap.sh
index cda21df..0c2b886 100755
--- a/bootstrap.sh
+++ b/bootstrap.sh
@@ -20,7 +20,11 @@
 #
 
 ./cleanup.sh
-(cd lib/php/src/ext/thrift_protocol && phpize)
+if test -d lib/php/src/ext/thrift_protocol ; then
+    if phpize -v >/dev/null 2>/dev/null ; then
+        (cd lib/php/src/ext/thrift_protocol && phpize)
+    fi
+fi
 
 set -e