radioInterface: Fix variable storing integer return value

Change-Id: I0a0a06a6d16a228cfcb7bd746bab2d79f10ce244
diff --git a/Transceiver52M/radioInterface.cpp b/Transceiver52M/radioInterface.cpp
index b9c6672..7d6a03b 100644
--- a/Transceiver52M/radioInterface.cpp
+++ b/Transceiver52M/radioInterface.cpp
@@ -304,7 +304,8 @@
 int RadioInterface::pullBuffer()
 {
   bool local_underrun;
-  size_t numRecv, segmentLen = recvBuffer[0]->getSegmentLen();
+  int numRecv;
+  size_t segmentLen = recvBuffer[0]->getSegmentLen();
 
   if (recvBuffer[0]->getFreeSegments() <= 0)
     return -1;
@@ -316,7 +317,7 @@
                                 readTimestamp,
                                 &local_underrun);
 
-  if (numRecv != segmentLen) {
+  if ((size_t) numRecv != segmentLen) {
           LOG(ALERT) << "Receive error " << numRecv;
           return -1;
   }