diff --git a/host/hackrf-tools/src/hackrf_transfer.c b/host/hackrf-tools/src/hackrf_transfer.c
index 41061ff0..399bbaef 100644
--- a/host/hackrf-tools/src/hackrf_transfer.c
+++ b/host/hackrf-tools/src/hackrf_transfer.c
@@ -629,7 +629,7 @@ static void usage()
 	printf("\t[-S buf_size] # Enable receive streaming with buffer size buf_size.\n");
 #endif
 	printf("\t[-B] # Print buffer statistics during transfer\n");
-	printf("\t[-c amplitude] # CW signal source mode, amplitude 0-128 (DC value to DAC).\n");
+	printf("\t[-c amplitude] # CW signal source mode, amplitude 0-127 (DC value to DAC).\n");
 	printf("\t[-R] # Repeat TX mode (default is off) \n");
 	printf("\t[-b baseband_filter_bw_hz] # Set baseband filter bandwidth in Hz.\n");
 	printf("\tPossible values: 1.75/2.5/3.5/5/5.5/6/7/8/9/10/12/14/15/20/24/28MHz, default <= 0.75 * sample_rate_hz.\n");
@@ -1019,9 +1019,9 @@ int main(int argc, char** argv)
 
 	if (signalsource) {
 		transceiver_mode = TRANSCEIVER_MODE_SS;
-		if (amplitude > 128) {
+		if (amplitude > 127) {
 			fprintf(stderr,
-				"argument error: amplitude must be between 0 and 128.\n");
+				"argument error: amplitude must be between 0 and 127.\n");
 			usage();
 			return EXIT_FAILURE;
 		}