diff --git a/include/utils.h b/include/utils.h
index 8080c6b70..a85121a61 100644
--- a/include/utils.h
+++ b/include/utils.h
@@ -93,10 +93,13 @@ double randf();
 char * strcatf(char **dest, const char *fmt, ...)
 	__attribute__ ((format(printf, 2, 3)));
 
-/** Variadic version of strcatv() */
+/** Variadic version of strcatf() */
 char * vstrcatf(char **dest, const char *fmt, va_list va)
 	__attribute__ ((format(printf, 2, 0)));
 
+/** Format string like strcatf() just starting with empty string */
+#define strf(fmt, ...) strcatf(&(void *) { NULL }, fmt, ##__VA_ARGS__)
+
 /** Format a struct timespec date similar to strftime() */
 int strftimespec(char *s, size_t max, const char *format, struct timespec *ts)
 	__attribute__ ((format(strftime, 3, 0)));
diff --git a/lib/gtfpga.c b/lib/gtfpga.c
index c456c77b5..fc94e3f54 100644
--- a/lib/gtfpga.c
+++ b/lib/gtfpga.c
@@ -100,16 +100,15 @@ int gtfpga_parse(struct node *n, config_setting_t *cfg)
 char * gtfpga_print(struct node *n)
 {
 	struct gtfpga *g = n->_vd;
-	char *buf = NULL;
 
 	if (g->dev) {
-		return strcatf(&buf, "rate=%.1f slot=%04"PRIx16":%02"PRIx8":%02"PRIx8".%"PRIx8
+		return strf("rate=%.1f slot=%04"PRIx16":%02"PRIx8":%02"PRIx8".%"PRIx8
 			" id=%04"PRIx16":%04"PRIx16" class=%04"PRIx16" irq=%d (%s)", g->rate,
 			g->dev->domain, g->dev->bus, g->dev->dev, g->dev->func, g->dev->vendor_id, g->dev->device_id,
 			g->dev->device_class, g->dev->irq, g->name);
 	}
 	else {
-		return strcatf(&buf, "rate=%.1f slot=%02"PRIx8":%02"PRIx8".%"PRIx8" id=%04"PRIx16":%04"PRIx16, g->rate,
+		return strf("rate=%.1f slot=%02"PRIx8":%02"PRIx8".%"PRIx8" id=%04"PRIx16":%04"PRIx16, g->rate,
 			g->filter.bus, g->filter.device, g->filter.func,
 			g->filter.vendor, g->filter.device);
 	}
diff --git a/lib/ngsi.c b/lib/ngsi.c
index 217d735bb..f87f1774b 100644
--- a/lib/ngsi.c
+++ b/lib/ngsi.c
@@ -472,9 +472,8 @@ int ngsi_parse(struct node *n, config_setting_t *cfg)
 char * ngsi_print(struct node *n)
 {
 	struct ngsi *i = n->_vd;
-	char *buf = NULL;
 
-	return strcatf(&buf, "endpoint=%s, timeout=%.3f secs, #mappings=%zu",
+	return strf("endpoint=%s, timeout=%.3f secs, #mappings=%zu",
 		i->endpoint, i->timeout, list_length(&i->mapping));
 }
 
diff --git a/lib/opal.c b/lib/opal.c
index 25d8e7182..76ccf586b 100644
--- a/lib/opal.c
+++ b/lib/opal.c
@@ -143,11 +143,10 @@ int opal_parse(struct node *n, config_setting_t *cfg)
 char * opal_print(struct node *n)
 {
 	struct opal *o = n->_vd;
-	char *buf = NULL;
 
 	/** @todo: Print send_params, recv_params */
 
-	return strcatf(&buf, "send_id=%u, recv_id=%u, reply=%u",
+	return strf("send_id=%u, recv_id=%u, reply=%u",
 		o->send_id, o->recv_id, o->reply);
 }
 
diff --git a/lib/socket.c b/lib/socket.c
index 3f90c82bd..a3e6e646f 100644
--- a/lib/socket.c
+++ b/lib/socket.c
@@ -96,7 +96,7 @@ int socket_deinit()
 char * socket_print(struct node *n)
 {
 	struct socket *s = n->_vd;
-	char *layer = NULL, *buf = NULL;
+	char *layer = NULL, *buf;
 	
 	switch (s->layer) {
 		case LAYER_UDP: layer = "udp";	break;
@@ -107,7 +107,7 @@ char * socket_print(struct node *n)
 	char *local = socket_print_addr((struct sockaddr *) &s->local);
 	char *remote = socket_print_addr((struct sockaddr *) &s->remote);
 
-	strcatf(&buf, "layer=%s, local=%s, remote=%s", layer, local, remote);
+	buf = strf("layer=%s, local=%s, remote=%s", layer, local, remote);
 	
 	free(local);
 	free(remote);