diff --git a/ChangeLog b/ChangeLog
index da002abce..b01e3c256 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2016-08-16  Werner Lemberg  <wl@gnu.org>
+
+	[lzw] Avoid invalid left shift.
+
+	* src/lzw/ftzopen.c (ft_lzwstate_get_code): Limit `num_bits'.
+
 2016-08-16  Werner Lemberg  <wl@gnu.org>
 
 	[lzw] Avoid buffer overrun.
diff --git a/src/lzw/ftzopen.c b/src/lzw/ftzopen.c
index 32839cc32..ae79fdd24 100644
--- a/src/lzw/ftzopen.c
+++ b/src/lzw/ftzopen.c
@@ -65,6 +65,9 @@
     FT_Int    result;
 
 
+    if ( num_bits > LZW_MAX_BITS )
+      return -1;
+
     if ( state->buf_clear                    ||
          offset >= state->buf_size           ||
          state->free_ent >= state->free_bits )