diff --git a/lib/cswrap.c b/lib/cswrap.c
index aab6375..16941de 100644
--- a/lib/cswrap.c
+++ b/lib/cswrap.c
@@ -60,10 +60,28 @@ void destroy_cstrwrap(sexp_cstrwrap_t *csw)
   return;
 }
 
+static inline void __rnc_buf(sexp_cstrwrap_t *wr)
+{
+  int sbuf_size = 0;
+
+  if(wr->sln - wr->cnt >= CSTRBUFSIZ) sbuf_size = CSTRBUFSIZ;
+  else sbuf_size = wr->sln - wr->cnt;
+
+  /*
+   * FIXME: is it ugly to copy?
+   * TODO: way to optimize is to modify a source string
+   * temproary - it's a way more worse
+   */
+  memcpy(wr->buf, wr->seval + wr->cnt, sbuf_size);
+  wr->cnt += sbuf_size;
+  wr->rl = sbuf_size;
+
+  return;
+}
+
 sexp_t *get_one_sexp(sexp_cstrwrap_t *wr)
 {
   sexp_t *sx = NULL;
-  int sbuf_size = 0;
 
   if(!wr) return NULL;
 
@@ -87,13 +105,7 @@ sexp_t *get_one_sexp(sexp_cstrwrap_t *wr)
       return NULL; /* we're done here */
     }
 
-    if(wr->sln - wr->cnt >= CSTRBUFSIZ) sbuf_size = CSTRBUFSIZ;
-    else sbuf_size = wr->sln - wr->cnt;
-
-    /* FIXME: it's ugly to copy TODO: optimize it there */
-    memcpy(wr->buf, wr->seval + wr->cnt, sbuf_size);
-    wr->cnt += sbuf_size;
-    wr->rl = sbuf_size;
+    __rnc_buf(wr);
   }
 
   wr->cc = cparse_sexp(wr->buf, wr->rl, wr->cc);
@@ -105,20 +117,13 @@ sexp_t *get_one_sexp(sexp_cstrwrap_t *wr)
       return NULL;
     }
 
-    /* TODO: FIXME: remove copy-n-paste */
     /* check for EOB */
     if(wr->sln == wr->cnt) {
       sexp_errno = SEXP_ERR_IO_EMPTY;
       return NULL; /* we're done here, s expression didn't finished */
     }
 
-    if(wr->sln - wr->cnt >= CSTRBUFSIZ) sbuf_size = CSTRBUFSIZ;
-    else sbuf_size = wr->sln - wr->cnt;
-
-    /* FIXME: it's ugly to copy TODO: optimize it there */
-    memcpy(wr->buf, wr->seval + wr->cnt, sbuf_size);
-    wr->cnt += sbuf_size;
-    wr->rl = sbuf_size;
+    __rnc_buf(wr);
 
     wr->cc = cparse_sexp(wr->buf, wr->rl, wr->cc);
     wr->rl = 0;