diff --git a/common/rfb/ZRLEEncoder.cxx b/common/rfb/ZRLEEncoder.cxx
index 896b83b..5ef54d2 100644
--- a/common/rfb/ZRLEEncoder.cxx
+++ b/common/rfb/ZRLEEncoder.cxx
@@ -26,9 +26,6 @@
 
 using namespace rfb;
 
-rdr::MemOutStream* ZRLEEncoder::sharedMos = 0;
-int ZRLEEncoder::maxLen = 4097 * 1024; // enough for width 16384 32-bit pixels
-
 IntParameter zlibLevel("ZlibLevel","Zlib compression level",-1);
 
 #define EXTRA_ARGS ImageGetter* ig
@@ -55,33 +52,27 @@
 }
 
 ZRLEEncoder::ZRLEEncoder(SMsgWriter* writer_)
-  : writer(writer_), zos(0,0,zlibLevel)
+  : writer(writer_), zos(0,0,zlibLevel), mos(129*1024)
 {
-  if (sharedMos)
-    mos = sharedMos;
-  else
-    mos = new rdr::MemOutStream(129*1024);
 }
 
 ZRLEEncoder::~ZRLEEncoder()
 {
-  if (!sharedMos)
-    delete mos;
 }
 
 bool ZRLEEncoder::writeRect(const Rect& r, TransImageGetter* ig, Rect* actual)
 {
   rdr::U8* imageBuf = writer->getImageBuf(64 * 64 * 4 + 4);
-  mos->clear();
+  mos.clear();
   bool wroteAll = true;
   *actual = r;
 
   switch (writer->bpp()) {
   case 8:
-    wroteAll = zrleEncode8(r, mos, &zos, imageBuf, maxLen, actual, ig);
+    wroteAll = zrleEncode8(r, &mos, &zos, imageBuf, actual, ig);
     break;
   case 16:
-    wroteAll = zrleEncode16(r, mos, &zos, imageBuf, maxLen, actual, ig);
+    wroteAll = zrleEncode16(r, &mos, &zos, imageBuf, actual, ig);
     break;
   case 32:
     {
@@ -94,16 +85,16 @@
       if ((fitsInLS3Bytes && pf.isLittleEndian()) ||
           (fitsInMS3Bytes && pf.isBigEndian()))
       {
-        wroteAll = zrleEncode24A(r, mos, &zos, imageBuf, maxLen, actual, ig);
+        wroteAll = zrleEncode24A(r, &mos, &zos, imageBuf, actual, ig);
       }
       else if ((fitsInLS3Bytes && pf.isBigEndian()) ||
                (fitsInMS3Bytes && pf.isLittleEndian()))
       {
-        wroteAll = zrleEncode24B(r, mos, &zos, imageBuf, maxLen, actual, ig);
+        wroteAll = zrleEncode24B(r, &mos, &zos, imageBuf, actual, ig);
       }
       else
       {
-        wroteAll = zrleEncode32(r, mos, &zos, imageBuf, maxLen, actual, ig);
+        wroteAll = zrleEncode32(r, &mos, &zos, imageBuf, actual, ig);
       }
       break;
     }
@@ -111,8 +102,8 @@
 
   writer->startRect(*actual, encodingZRLE);
   rdr::OutStream* os = writer->getOutStream();
-  os->writeU32(mos->length());
-  os->writeBytes(mos->data(), mos->length());
+  os->writeU32(mos.length());
+  os->writeBytes(mos.data(), mos.length());
   writer->endRect();
   return wroteAll;
 }
diff --git a/common/rfb/ZRLEEncoder.h b/common/rfb/ZRLEEncoder.h
index 3a0f52a..61ff6fb 100644
--- a/common/rfb/ZRLEEncoder.h
+++ b/common/rfb/ZRLEEncoder.h
@@ -30,25 +30,11 @@
     virtual bool writeRect(const Rect& r, TransImageGetter* ig, Rect* actual);
     virtual ~ZRLEEncoder();
 
-    // setMaxLen() sets the maximum size in bytes of any ZRLE rectangle.  This
-    // can be used to stop the MemOutStream from growing too large.  The value
-    // must be large enough to allow for at least one row of ZRLE tiles.  So
-    // for example for a screen width of 2048 32-bit pixels this is 2K*4*64 =
-    // 512Kbytes plus a bit of overhead (the overhead is about 1/16 of the
-    // width, in this example about 128 bytes).
-    static void setMaxLen(int m) { maxLen = m; }
-
-    // setSharedMos() sets a MemOutStream to be shared amongst all
-    // ZRLEEncoders.  Should be called before any ZRLEEncoders are created.
-    static void setSharedMos(rdr::MemOutStream* mos_) { sharedMos = mos_; }
-
   private:
     ZRLEEncoder(SMsgWriter* writer);
     SMsgWriter* writer;
     rdr::ZlibOutStream zos;
-    rdr::MemOutStream* mos;
-    static rdr::MemOutStream* sharedMos;
-    static int maxLen;
+    rdr::MemOutStream mos;
   };
 }
 #endif
diff --git a/common/rfb/zrleEncode.h b/common/rfb/zrleEncode.h
index 9b7263b..0c622b8 100644
--- a/common/rfb/zrleEncode.h
+++ b/common/rfb/zrleEncode.h
@@ -115,7 +115,7 @@
 void ZRLE_ENCODE_TILE (PIXEL_T* data, int w, int h, rdr::OutStream* os);
 
 bool ZRLE_ENCODE (const Rect& r, rdr::OutStream* os,
-                  rdr::ZlibOutStream* zos, void* buf, int maxLen, Rect* actual
+                  rdr::ZlibOutStream* zos, void* buf, Rect* actual
 #ifdef EXTRA_ARGS
                   , EXTRA_ARGS
 #endif
@@ -132,7 +132,8 @@
 
     t.br.y = __rfbmin(r.br.y, t.tl.y + 64);
 
-    if (os->length() + worstCaseLine > maxLen) {
+    // enough for width 16384 32-bit pixels
+    if (os->length() + worstCaseLine > 4097 * 1024) {
       if (t.tl.y == r.tl.y)
         throw Exception("ZRLE: not enough space for first line?");
       actual->tl = r.tl;