diff --git a/Makefile b/Makefile
index 297cd12..c8c373b 100644
--- a/Makefile
+++ b/Makefile
@@ -112,7 +112,7 @@ rinreport: rinreport.o rinex.o githash.o navmon.o ext/fmt-6.1.2/src/format.o  ep
 	$(CXX) -std=gnu++17 $^ -o $@ -lz -pthread
 
 rtcmtool: rtcmtool.o navmon.pb.o githash.o ext/fmt-6.1.2/src/format.o  bits.o nmmsender.o $(SIMPLESOCKETS)  navmon.o rtcm.o zstdwrap.o
-	$(CXX) -std=gnu++17 $^ -o $@ -lz -pthread -lprotobuf -lzstd
+	$(CXX) -std=gnu++17 $^ -o $@ -L/usr/local/lib -lz -pthread -lprotobuf -lzstd
 
 
 ubxtool: navmon.pb.o ubxtool.o ubx.o bits.o ext/fmt-6.1.2/src/format.o galileo.o  gps.o beidou.o navmon.o ephemeris.o $(SIMPLESOCKETS) osen.o githash.o nmmsender.o zstdwrap.o 
diff --git a/nmmsender.cc b/nmmsender.cc
index 5334b21..0d3ea3e 100644
--- a/nmmsender.cc
+++ b/nmmsender.cc
@@ -38,6 +38,12 @@ void NMMSender::sendTCPThread(Destination* d)
         SocketCommunicator sc(s);
         sc.setTimeout(3);
         sc.connect(addr);
+
+#if !defined(TCP_CORK) && defined(TCP_NOPUSH)
+	/* start off "buffering" */
+        SSetsockopt(s, IPPROTO_TCP, TCP_NOPUSH, 1 );
+#endif
+
         time_t connStartTime = time(0);
         if (d_debug) { cerr<<humanTimeNow()<<" Connected to "<<d->dst<<" on "<<addr.toStringWithPort()<<endl; }
         auto emit = [&sc](const char*buf, uint32_t len) {
@@ -112,8 +118,20 @@ void NMMSender::sendTCPThread(Destination* d)
             }
             hadMessage = false;
             usleep(100000);
-#ifdef __linux__
+#if defined(TCP_CORK)
+	    /* linux-only: has an implied 200ms timeout */
             SSetsockopt(s, IPPROTO_TCP, TCP_CORK, 1 );
+#elif defined(TCP_NOPUSH)
+	    /*
+	     * freebsd/osx: buffers until buffer full/connection closed, so
+	     * we toggle it every other loop through
+	     */
+	    static bool push_toggle;
+	    if (push_toggle) {
+		    SSetsockopt(s, IPPROTO_TCP, TCP_NOPUSH, 0 );
+		    SSetsockopt(s, IPPROTO_TCP, TCP_NOPUSH, 1 );
+	    }
+	    push_toggle = !push_toggle;
 #endif
 
           }