diff --git a/QnetGateway.cpp b/QnetGateway.cpp
index b87b5b6..26db4b8 100644
--- a/QnetGateway.cpp
+++ b/QnetGateway.cpp
@@ -999,12 +999,14 @@ void CQnetGateway::ProcessIncomingSD(const SDSVT &dsvt)
 			case 0x30U:	// GPS data
 				if (sd.size + sd.ig < 255) {
 					memcpy(sd.gps+sd.ig, c+1, size);
-					sd.ig += size;
-					sd.size -= size;
 					if (c[1]=='\r' || c[2]=='\r') {
 						sd.gps[sd.ig + (c[1] == '\r') ? 0 : 1] = '\0';
 						printf("GPS[%d] String='%s'\n", i, sd.gps);
+						memset(sd.gps, 0, 256);
 						sd.ig = sd.size = 0;
+					} else {
+						sd.ig += size;
+						sd.size -= size;
 					}
 				} else {
 					printf("GPS string is too large at %d bytes\n", sd.ig + sd.size);
@@ -1058,6 +1060,7 @@ void CQnetGateway::ProcessIncomingSD(const SDSVT &dsvt)
 					else
 						sd.gps[sd.ig+2] = '\0';
 					printf("GPS[%d] string='%s'\n", i, sd.gps);
+					memset(sd.gps, 0, 256);
 					sd.ig = 0;
 				} else {
 					sd.ig += sd.size;