diff --git a/mosquitto.c b/mosquitto.c
index 8e47fe2..be64b47 100644
--- a/mosquitto.c
+++ b/mosquitto.c
@@ -117,7 +117,11 @@ PHP_METHOD(Mosquitto_Client, __construct)
 	if (!object->client) {
 		char *message = php_mosquitto_strerror_wrapper(errno);
 		zend_throw_exception(mosquitto_ce_exception, message, 1 TSRMLS_CC);
-		efree(message);
+#ifndef STRERROR_R_CHAR_P
+		if (message != NULL) {
+			efree(message);
+		}
+#endif
 	}
 }
 /* }}} */
@@ -835,10 +839,11 @@ static int strerror_r(int errnum, char *buf, size_t buf_len)
 
 PHP_MOSQUITTO_API char *php_mosquitto_strerror_wrapper(int err)
 {
-	char *buf = ecalloc(256, sizeof(char));
+	char *buf;
 #ifdef STRERROR_R_CHAR_P
 	return strerror_r(err, buf, 256);
 #else
+	buf = ecalloc(256, sizeof(char));
 	if (!strerror_r(err, buf, 256)) {
 		return buf;
 	}
diff --git a/travis/run-tests.sh b/travis/run-tests.sh
index dabee72..3bbe974 100755
--- a/travis/run-tests.sh
+++ b/travis/run-tests.sh
@@ -9,4 +9,4 @@ cd tests
 mosquitto -c mosquitto.conf -d
 cd ..
 
-REPORT_EXIT_STATUS=1 TEST_PHP_ARGS="-q --show-diff" make test
+USE_ZEND_ALLOC=1 REPORT_EXIT_STATUS=1 TEST_PHP_ARGS="-q --show-diff" make test