diff --git a/src/out_format.c b/src/out_format.c
index 19c588f..84a5a2b 100644
--- a/src/out_format.c
+++ b/src/out_format.c
@@ -126,10 +126,10 @@ static char *get_token(struct element_group *g, struct element *e,
 		}
 
 		if (!strncasecmp(type, "rx:", 3)) {
-			snprintf(buf, len, "%llu", a->a_rx_rate.r_total);
+			snprintf(buf, len, "%" PRIu64, a->a_rx_rate.r_total);
 			return buf;
 		} else if (!strncasecmp(type, "tx:", 3)) {
-			snprintf(buf, len, "%llu", a->a_tx_rate.r_total);
+			snprintf(buf, len, "%" PRIu64, a->a_tx_rate.r_total);
 			return buf;
 		} else if (!strncasecmp(type, "rxrate:", 7)) {
 			snprintf(buf, len, "%.2f", a->a_rx_rate.r_rate);
diff --git a/src/unit.c b/src/unit.c
index 6f3c577..38fc468 100644
--- a/src/unit.c
+++ b/src/unit.c
@@ -191,7 +191,7 @@ char *unit_bytes2str(uint64_t bytes, char *buf, size_t len)
 		v = unit_value2str(bytes, byte_unit, &ustr, &prec);
 		snprintf(buf, len, "%'.*f%3s", prec, v, ustr);
 	} else
-		snprintf(buf, len, "%llu", (unsigned long long) bytes);
+		snprintf(buf, len, "%" PRIu64, bytes);
 
 	return buf;
 }
@@ -206,7 +206,7 @@ char *unit_bit2str(uint64_t bits, char *buf, size_t len)
 		v = unit_value2str(bits, bit_unit, &ustr, &prec);
 		snprintf(buf, len, "%'.*f%3s", prec, v, ustr);
 	} else
-		snprintf(buf, len, "%llu", (unsigned long long) bits);
+		snprintf(buf, len, "%" PRIu64, bits);
 
 	return buf;
 }