diff --git a/sim/SimRsim.c b/sim/SimRsim.c
index f06cc1cf..653db1bf 100644
--- a/sim/SimRsim.c
+++ b/sim/SimRsim.c
@@ -629,7 +629,7 @@ SimFillBuffer(
     int 	charsRead = 0;
     char 	*temp;
     int		n, nfd;
-#if defined(SYSV) || defined(CYGWIN) || defined(__FreeBSD__) || defined(__APPLE__)
+#if defined(SYSV) || defined(CYGWIN) || defined(__FreeBSD__) || defined(__APPLE__) || defined(EMSCRIPTEN)
     fd_set readfds, writefds, exceptfds;
 #else
     int		nr, nex;
@@ -645,7 +645,7 @@ SimFillBuffer(
 
     /* read reply from Rsim */
 
-#if defined(SYSV) || defined(CYGWIN) || defined(__FreeBSD__) || defined(__APPLE__)
+#if defined(SYSV) || defined(CYGWIN) || defined(__FreeBSD__) || defined(__APPLE__) || defined(EMSCRIPTEN)
     FD_ZERO(&readfds);
     FD_ZERO(&exceptfds);
 #endif  /* SYSV */
@@ -661,7 +661,7 @@ SimFillBuffer(
 
 try_again:
 
-#if defined(SYSV) || defined(CYGWIN) || defined(__FreeBSD__) || defined(__APPLE__)
+#if defined(SYSV) || defined(CYGWIN) || defined(__FreeBSD__) || defined(__APPLE__) || defined(EMSCRIPTEN)
     FD_SET(pipeIn, &readfds);
     FD_ZERO(&writefds);
     FD_SET(pipeIn, &exceptfds);
@@ -669,7 +669,7 @@ try_again:
 
 #else /* !SYSV */
     nr = nex = 1 << pipeIn;
-    n = select(nfd, &nr, (int *) NULL, &nex, &timeout);
+    n = select(nfd, &nr, NULL, &nex, &timeout);
 
 #endif