diff --git a/patchlevel.h b/patchlevel.h
--- a/patchlevel.h
+++ b/patchlevel.h
@@ -25,6 +25,6 @@
    regexp `^#define[ 	]*PATCHLEVEL', since that's what support/mkversion.sh
    looks for to find the patch level (for the sccs version string). */
 
-#define PATCHLEVEL 20
+#define PATCHLEVEL 21
 
 #endif /* _PATCHLEVEL_H_ */
diff --git a/subst.c b/subst.c
--- a/subst.c
+++ b/subst.c
@@ -1693,7 +1693,7 @@ extract_heredoc_dolbrace_string (string, sindex, quoted, flags)
 	  t = extract_command_subst (string, &si, flags);
 	  CHECK_STRING_OVERRUN (i, si, slen, c);
 
-	  tlen = si - i - 1;
+	  tlen = si - i - 2;
 	  RESIZE_MALLOCED_BUFFER (result, result_index, tlen + 4, result_size, 64);
 	  result[result_index++] = c;
 	  result[result_index++] = LPAREN;
@@ -1713,7 +1713,7 @@ extract_heredoc_dolbrace_string (string, sindex, quoted, flags)
 	  t = extract_process_subst (string, (string[i] == '<' ? "<(" : ">)"), &si, flags);
 	  CHECK_STRING_OVERRUN (i, si, slen, c);
 
-	  tlen = si - i - 1;
+	  tlen = si - i - 2;
 	  RESIZE_MALLOCED_BUFFER (result, result_index, tlen + 4, result_size, 64);
 	  result[result_index++] = c;
 	  result[result_index++] = LPAREN;