diff --git a/drivers/w1/slaves/w1_therm.c b/drivers/w1/slaves/w1_therm.c
index 4318935..feed89e 100644
--- a/drivers/w1/slaves/w1_therm.c
+++ b/drivers/w1/slaves/w1_therm.c
@@ -112,7 +112,7 @@
 
 static inline int w1_DS18B20_convert_temp(u8 rom[9])
 {
-	int t = (rom[1] << 8) | rom[0];
+	s16 t = (rom[1] << 8) | rom[0];
 	t /= 16;
 	return t;
 }