diff --git a/src/ca/client/udpiiu.cpp b/src/ca/client/udpiiu.cpp
index beae07560..ccb2556e8 100644
--- a/src/ca/client/udpiiu.cpp
+++ b/src/ca/client/udpiiu.cpp
@@ -165,7 +165,7 @@ udpiiu::udpiiu (
 
 #ifdef IP_ADD_MEMBERSHIP
     {
-        int flag = 1;
+        osiSockOptMcastLoop_t flag = 1;
         if ( setsockopt ( this->sock, IPPROTO_IP, IP_MULTICAST_LOOP,
                           (char *) &flag, sizeof ( flag ) ) == -1 ) {
             char sockErrBuf[64];
diff --git a/src/ioc/rsrv/caservertask.c b/src/ioc/rsrv/caservertask.c
index 50bc650c2..fda442168 100644
--- a/src/ioc/rsrv/caservertask.c
+++ b/src/ioc/rsrv/caservertask.c
@@ -308,7 +308,7 @@ void rsrv_build_addr_lists(void)
         }
 #ifdef IP_ADD_MEMBERSHIP
         {
-            int flag = 1;
+            osiSockOptMcastLoop_t flag = 1;
             if (setsockopt(beaconSocket, IPPROTO_IP, IP_MULTICAST_LOOP,
                            (char *)&flag, sizeof(flag))<0) {
                 char sockErrBuf[64];
diff --git a/src/libCom/osi/os/Darwin/osdSock.h b/src/libCom/osi/os/Darwin/osdSock.h
index 1d4556eee..e7c344062 100644
--- a/src/libCom/osi/os/Darwin/osdSock.h
+++ b/src/libCom/osi/os/Darwin/osdSock.h
@@ -31,6 +31,7 @@ typedef int                     SOCKET;
 #define socket_ioctl(A,B,C)     ioctl(A,B,C)
 typedef int osiSockIoctl_t;
 typedef socklen_t osiSocklen_t;
+typedef int osiSockOptMcastLoop_t;
 
 #define FD_IN_FDSET(FD) ((FD)<FD_SETSIZE)
 
diff --git a/src/libCom/osi/os/Linux/osdSock.h b/src/libCom/osi/os/Linux/osdSock.h
index 614f3f98d..7164a54ee 100644
--- a/src/libCom/osi/os/Linux/osdSock.h
+++ b/src/libCom/osi/os/Linux/osdSock.h
@@ -35,6 +35,7 @@ typedef int                     SOCKET;
 #define socket_ioctl(A,B,C)     ioctl(A,B,C)
 typedef int osiSockIoctl_t;
 typedef socklen_t osiSocklen_t;
+typedef int osiSockOptMcastLoop_t;
 
 #define FD_IN_FDSET(FD) ((FD)<FD_SETSIZE)
 
diff --git a/src/libCom/osi/os/RTEMS/osdSock.h b/src/libCom/osi/os/RTEMS/osdSock.h
index 930ed0e72..6177c3033 100644
--- a/src/libCom/osi/os/RTEMS/osdSock.h
+++ b/src/libCom/osi/os/RTEMS/osdSock.h
@@ -42,6 +42,7 @@ typedef int                     SOCKET;
 #define socket_ioctl(A,B,C)     ioctl(A,B,C)
 typedef int osiSockIoctl_t;
 typedef socklen_t osiSocklen_t;
+typedef char osiSockOptMcastLoop_t;
 
 #define FD_IN_FDSET(FD) ((FD)<FD_SETSIZE)
 
diff --git a/src/libCom/osi/os/WIN32/osdSock.h b/src/libCom/osi/os/WIN32/osdSock.h
index d92e18755..2ff23c4a6 100644
--- a/src/libCom/osi/os/WIN32/osdSock.h
+++ b/src/libCom/osi/os/WIN32/osdSock.h
@@ -28,6 +28,7 @@
 #define socket_ioctl(A,B,C)	ioctlsocket(A,B,C)
 typedef u_long FAR osiSockIoctl_t;
 typedef int osiSocklen_t;
+typedef BOOL osiSockOptMcastLoop_t;
 
 #ifndef SHUT_RD
 #   define SHUT_RD SD_RECEIVE
diff --git a/src/libCom/osi/os/cygwin32/osdSock.h b/src/libCom/osi/os/cygwin32/osdSock.h
index d642cad44..75288c865 100644
--- a/src/libCom/osi/os/cygwin32/osdSock.h
+++ b/src/libCom/osi/os/cygwin32/osdSock.h
@@ -34,6 +34,7 @@ typedef int                     SOCKET;
 #define socket_ioctl(A,B,C)     ioctl(A,B,C)
 typedef int osiSockIoctl_t;
 typedef int osiSocklen_t;
+typedef int osiSockOptMcastLoop_t;
 #define FD_IN_FDSET(FD) ((FD)<FD_SETSIZE&&(FD)>=0)
 #ifndef SHUT_RD
 #define SHUT_RD 0
diff --git a/src/libCom/osi/os/freebsd/osdSock.h b/src/libCom/osi/os/freebsd/osdSock.h
index fe28d4cd5..b402ec120 100644
--- a/src/libCom/osi/os/freebsd/osdSock.h
+++ b/src/libCom/osi/os/freebsd/osdSock.h
@@ -36,6 +36,7 @@ typedef int                     SOCKET;
 #define socket_ioctl(A,B,C)     ioctl(A,B,C)
 typedef int osiSockIoctl_t;
 typedef socklen_t osiSocklen_t;
+typedef int osiSockOptMcastLoop_t;
 
 #define FD_IN_FDSET(FD) ((FD)<FD_SETSIZE)
 
diff --git a/src/libCom/osi/os/iOS/osdSock.h b/src/libCom/osi/os/iOS/osdSock.h
index 0b3b3f6c1..08849a8d8 100644
--- a/src/libCom/osi/os/iOS/osdSock.h
+++ b/src/libCom/osi/os/iOS/osdSock.h
@@ -32,6 +32,7 @@ typedef int                     SOCKET;
 #define socket_ioctl(A,B,C)     ioctl(A,B,C)
 typedef int osiSockIoctl_t;
 typedef socklen_t osiSocklen_t;
+typedef int osiSockOptMcastLoop_t;
 
 #define FD_IN_FDSET(FD) ((FD)<FD_SETSIZE)
 
diff --git a/src/libCom/osi/os/solaris/osdSock.h b/src/libCom/osi/os/solaris/osdSock.h
index a39c6c3d3..872a08df5 100644
--- a/src/libCom/osi/os/solaris/osdSock.h
+++ b/src/libCom/osi/os/solaris/osdSock.h
@@ -42,6 +42,7 @@ typedef int osiSockIoctl_t;
 #else
     typedef int osiSocklen_t;
 #endif
+typedef int osiSockOptMcastLoop_t;
 
 #define DOES_NOT_ACCEPT_ZERO_LENGTH_UDP
 
diff --git a/src/libCom/osi/os/vxWorks/osdSock.h b/src/libCom/osi/os/vxWorks/osdSock.h
index 80464ef87..d949b25f1 100644
--- a/src/libCom/osi/os/vxWorks/osdSock.h
+++ b/src/libCom/osi/os/vxWorks/osdSock.h
@@ -65,6 +65,7 @@ typedef int                     SOCKET;
 #define socket_ioctl(A,B,C)     ioctl(A,B,(int)C)
 typedef int osiSockIoctl_t;
 typedef int osiSocklen_t;
+typedef int osiSockOptMcastLoop_t;
 
 #define FD_IN_FDSET(FD) ((FD)<FD_SETSIZE&&(FD)>=0)
 
diff --git a/src/libCom/test/Makefile b/src/libCom/test/Makefile
index ee4d11071..1ce7a6431 100755
--- a/src/libCom/test/Makefile
+++ b/src/libCom/test/Makefile
@@ -210,6 +210,11 @@ ipAddrToAsciiTest_SRCS += ipAddrToAsciiTest.cpp
 testHarness_SRCS += ipAddrToAsciiTest.cpp
 TESTS += ipAddrToAsciiTest
 
+TESTPROD_HOST += osiSockTest
+osiSockTest_SRCS += osiSockTest.c
+testHarness_SRCS += osiSockTest.c
+TESTS += osiSockTest
+
 # The testHarness runs all the test programs in a known working order.
 testHarness_SRCS += epicsRunLibComTests.c
 
@@ -254,4 +259,3 @@ cvtFastPerform_SRCS += cvtFastPerform.cpp
 testHarness_SRCS += cvtFastPerform.cpp
 
 include $(TOP)/configure/RULES
-
diff --git a/src/libCom/test/epicsRunLibComTests.c b/src/libCom/test/epicsRunLibComTests.c
index c4a76e777..29c5eda3f 100644
--- a/src/libCom/test/epicsRunLibComTests.c
+++ b/src/libCom/test/epicsRunLibComTests.c
@@ -51,6 +51,7 @@ int epicsInlineTest(void);
 int ipAddrToAsciiTest(void);
 int macDefExpandTest(void);
 int macLibTest(void);
+int osiSockTest(void);
 int ringBytesTest(void);
 int ringPointerTest(void);
 int taskwdTest(void);
@@ -104,6 +105,7 @@ void epicsRunLibComTests(void)
     runTest(ipAddrToAsciiTest);
     runTest(macDefExpandTest);
     runTest(macLibTest);
+    runTest(osiSockTest);
     runTest(ringBytesTest);
     runTest(ringPointerTest);
     runTest(taskwdTest);
diff --git a/src/libCom/test/osiSockTest.c b/src/libCom/test/osiSockTest.c
new file mode 100644
index 000000000..d9bbd29f7
--- /dev/null
+++ b/src/libCom/test/osiSockTest.c
@@ -0,0 +1,59 @@
+/*************************************************************************\
+* Copyright (c) 2017 UChicago Argonne LLC, as Operator of Argonne
+*     National Laboratory.
+* EPICS BASE is distributed subject to a Software License Agreement found
+* in file LICENSE that is included with this distribution.
+\*************************************************************************/
+
+#include <string.h>
+#include <stdio.h>
+
+#include "osiSock.h"
+#include "epicsUnitTest.h"
+#include "testMain.h"
+
+void udpSockTest(void)
+{
+    SOCKET s;
+    int status, one = 1, get = 0;
+    osiSocklen_t len;
+    osiSockOptMcastLoop_t flag = 1;
+
+    s = epicsSocketCreate(AF_INET, SOCK_DGRAM, 0);
+    testOk(s != INVALID_SOCKET, "epicsSocketCreate INET, DGRAM, 0");
+
+    status = setsockopt(s, SOL_SOCKET, SO_BROADCAST, (char *)&one, sizeof(one));
+    testOk(status >= 0, "setsockopt BROADCAST, 1");
+
+    len = sizeof(get);
+    status = getsockopt(s, SOL_SOCKET, SO_BROADCAST, (char *)&get, &len);
+    testOk(status >= 0 && len == sizeof(get) && get == 1,
+        "getsockopt BROADCAST == 1");
+
+    status = setsockopt(s, IPPROTO_IP, IP_MULTICAST_LOOP,
+                   (char *)&flag, sizeof(flag));
+    testOk(status >= 0, "setsockopt MULTICAST_LOOP, 1");
+
+    flag = 0;
+    len = sizeof(flag);
+    status = getsockopt(s, IPPROTO_IP, IP_MULTICAST_LOOP, (char *)&flag, &len);
+    testOk(status >= 0 && len == sizeof(flag) && flag == 1,
+        "getsockopt MULTICAST_LOOP == 1");
+
+    epicsSocketDestroy(s);
+}
+
+
+MAIN(osiSockTest)
+{
+    int status;
+    testPlan(6);
+
+    status = osiSockAttach();
+    testOk(status, "osiSockAttach");
+
+    udpSockTest();
+
+    osiSockRelease();
+    return testDone();
+}