diff --git a/include/msgpack/zbuffer.h b/include/msgpack/zbuffer.h
index dbad72c5..dbad8591 100644
--- a/include/msgpack/zbuffer.h
+++ b/include/msgpack/zbuffer.h
@@ -131,7 +131,7 @@ int msgpack_zbuffer_write(void* data, const char* buf, size_t len)
     zbuf->stream.next_in = (Bytef*)buf;
     zbuf->stream.avail_in = len;
 
-    do {
+    while(zbuf->stream.avail_in > 0) {
         if(zbuf->stream.avail_out < MSGPACK_ZBUFFER_RESERVE_SIZE) {
             if(!msgpack_zbuffer_expand(zbuf)) {
                 return -1;
@@ -141,7 +141,7 @@ int msgpack_zbuffer_write(void* data, const char* buf, size_t len)
         if(deflate(&zbuf->stream, Z_NO_FLUSH) != Z_OK) {
             return -1;
         }
-    } while(zbuf->stream.avail_in > 0);
+    }
 
     return 0;
 }
diff --git a/include/msgpack/zbuffer.hpp b/include/msgpack/zbuffer.hpp
index 688a70b5..71880648 100644
--- a/include/msgpack/zbuffer.hpp
+++ b/include/msgpack/zbuffer.hpp
@@ -65,7 +65,7 @@ public:
         m_stream.next_in = reinterpret_cast<Bytef*>(const_cast<char*>(buf));
         m_stream.avail_in = len;
 
-        do {
+        while(m_stream.avail_in > 0) {
             if(m_stream.avail_out < MSGPACK_ZBUFFER_RESERVE_SIZE) {
                 if(!expand()) {
                     throw std::bad_alloc();
@@ -75,7 +75,7 @@ public:
             if(deflate(&m_stream, Z_NO_FLUSH) != Z_OK) {
                 throw std::bad_alloc();
             }
-        } while(m_stream.avail_in > 0);
+        }
     }
 
     char* flush()