diff --git a/src/platform/wifi/wifi-utils-wext.c b/src/platform/wifi/wifi-utils-wext.c
index 96bcf53d26..85a387fae2 100644
--- a/src/platform/wifi/wifi-utils-wext.c
+++ b/src/platform/wifi/wifi-utils-wext.c
@@ -315,7 +315,7 @@ wext_qual_to_percent (const struct iw_quality *qual,
 			noise = qual->noise - 0x100;
 		else if ((max_qual->noise > 0) && !(max_qual->updated & IW_QUAL_NOISE_INVALID))
 			noise = max_qual->noise - 0x100;
-		noise = CLAMP (noise, FALLBACK_NOISE_FLOOR_DBM, FALLBACK_SIGNAL_MAX_DBM);
+		noise = CLAMP (noise, FALLBACK_NOISE_FLOOR_DBM, FALLBACK_SIGNAL_MAX_DBM - 1);
 
 		/* A sort of signal-to-noise ratio calculation */
 		level_percent = (int) (100 - 70 * (((double)max_level - (double)level) /