diff --git a/src/hb-buffer.cc b/src/hb-buffer.cc
index 88e113760..7401213e3 100644
--- a/src/hb-buffer.cc
+++ b/src/hb-buffer.cc
@@ -301,10 +301,9 @@ hb_buffer_t::clear ()
   memset (context, 0, sizeof context);
   memset (context_len, 0, sizeof context_len);
 
-  scratch_flags = HB_BUFFER_SCRATCH_FLAG_DEFAULT;
-  serial = 0;
-
   deallocate_var_all ();
+  serial = 0;
+  scratch_flags = HB_BUFFER_SCRATCH_FLAG_DEFAULT;
 }
 
 void
diff --git a/src/hb-buffer.hh b/src/hb-buffer.hh
index 5a6417cc8..f2cbc7580 100644
--- a/src/hb-buffer.hh
+++ b/src/hb-buffer.hh
@@ -129,11 +129,14 @@ struct hb_buffer_t
    * Not part of content.
    */
 
+#ifndef HB_NDEBUG
+  uint8_t allocated_var_bits;
+#endif
+  uint8_t serial;
   hb_buffer_scratch_flags_t scratch_flags; /* Have space-fallback, etc. */
-  unsigned int serial;
-
   unsigned int max_len; /* Maximum allowed len. */
   int max_ops; /* Maximum allowed operations. */
+  /* The bits here reflect current allocations of the bytes in glyph_info_t's var1 and var2. */
 
   /* Debugging API */
 #ifndef HB_NO_BUFFER_MESSAGE
@@ -145,11 +148,6 @@ struct hb_buffer_t
   static constexpr unsigned message_depth = 0u;
 #endif
 
-  /* Internal debugging. */
-  /* The bits here reflect current allocations of the bytes in glyph_info_t's var1 and var2. */
-#ifndef HB_NDEBUG
-  uint8_t allocated_var_bits;
-#endif
 
 
   /* Methods */
@@ -207,7 +205,7 @@ struct hb_buffer_t
 
   unsigned int backtrack_len () const { return have_output ? out_len : idx; }
   unsigned int lookahead_len () const { return len - idx; }
-  unsigned int next_serial () { return serial++; }
+  uint8_t next_serial () { return ++serial ? serial : ++serial; }
 
   HB_INTERNAL void add (hb_codepoint_t  codepoint,
 			unsigned int    cluster);
diff --git a/src/hb-ot-layout.hh b/src/hb-ot-layout.hh
index 2c825e0c8..ede8f007d 100644
--- a/src/hb-ot-layout.hh
+++ b/src/hb-ot-layout.hh
@@ -482,10 +482,9 @@ _hb_glyph_info_get_lig_num_comps (const hb_glyph_info_t *info)
 }
 
 static inline uint8_t
-_hb_allocate_lig_id (hb_buffer_t *buffer) {
+_hb_allocate_lig_id (hb_buffer_t *buffer)
+{
   uint8_t lig_id = buffer->next_serial () & 0x07;
-  if (unlikely (!lig_id))
-    lig_id = _hb_allocate_lig_id (buffer); /* in case of overflow */
   return lig_id;
 }
 
diff --git a/src/hb-ot-shape.cc b/src/hb-ot-shape.cc
index 4dde3520d..dc66d2c8c 100644
--- a/src/hb-ot-shape.cc
+++ b/src/hb-ot-shape.cc
@@ -1146,6 +1146,7 @@ static void
 hb_ot_shape_internal (hb_ot_shape_context_t *c)
 {
   c->buffer->deallocate_var_all ();
+  c->buffer->serial = 0;
   c->buffer->scratch_flags = HB_BUFFER_SCRATCH_FLAG_DEFAULT;
   if (likely (!hb_unsigned_mul_overflows (c->buffer->len, HB_BUFFER_MAX_LEN_FACTOR)))
   {
@@ -1191,6 +1192,7 @@ hb_ot_shape_internal (hb_ot_shape_context_t *c)
   c->buffer->max_len = HB_BUFFER_MAX_LEN_DEFAULT;
   c->buffer->max_ops = HB_BUFFER_MAX_OPS_DEFAULT;
   c->buffer->deallocate_var_all ();
+  c->buffer->serial = 0;
 }