diff --git a/release/c/wuffs-unsupported-snapshot.c b/release/c/wuffs-unsupported-snapshot.c
index 959ea16..901504e 100644
--- a/release/c/wuffs-unsupported-snapshot.c
+++ b/release/c/wuffs-unsupported-snapshot.c
@@ -8620,7 +8620,7 @@
   switch (coro_susp_point) {
     WUFFS_BASE__COROUTINE_SUSPENSION_POINT_0;
 
-    if (self->private_impl.f_call_sequence >= 1) {
+    if (self->private_impl.f_call_sequence >= 3) {
       status = wuffs_base__error__bad_call_sequence;
       goto exit;
     }
@@ -8651,7 +8651,7 @@
           self->private_impl.f_height,
           self->private_impl.f_frame_config_io_position, v_ffio);
     }
-    self->private_impl.f_call_sequence = 1;
+    self->private_impl.f_call_sequence = 3;
 
     goto ok;
   ok:
@@ -8822,8 +8822,8 @@
         if (status) {
           goto suspend;
         }
-      } else if (self->private_impl.f_call_sequence != 1) {
-        if (self->private_impl.f_call_sequence == 2) {
+      } else if (self->private_impl.f_call_sequence != 3) {
+        if (self->private_impl.f_call_sequence == 4) {
           WUFFS_BASE__COROUTINE_SUSPENSION_POINT(2);
           status = wuffs_gif__decoder__skip_frame(self, a_src);
           if (status) {
@@ -8864,7 +8864,7 @@
     }
     wuffs_base__u64__sat_add_indirect(
         &self->private_impl.f_num_decoded_frame_configs_value, 1);
-    self->private_impl.f_call_sequence = 2;
+    self->private_impl.f_call_sequence = 4;
 
     goto ok;
   ok:
@@ -9015,7 +9015,7 @@
   switch (coro_susp_point) {
     WUFFS_BASE__COROUTINE_SUSPENSION_POINT_0;
 
-    if (self->private_impl.f_call_sequence != 2) {
+    if (self->private_impl.f_call_sequence != 4) {
       WUFFS_BASE__COROUTINE_SUSPENSION_POINT(1);
       status = wuffs_gif__decoder__decode_frame_config(self, NULL, a_src);
       if (status) {
@@ -9059,7 +9059,7 @@
 
 static wuffs_base__empty_struct  //
 wuffs_gif__decoder__reset_gc(wuffs_gif__decoder* self) {
-  self->private_impl.f_call_sequence = 3;
+  self->private_impl.f_call_sequence = 5;
   self->private_impl.f_seen_graphic_control = false;
   self->private_impl.f_gc_has_transparent_index = false;
   self->private_impl.f_gc_transparent_index = 0;
diff --git a/std/gif/decode_gif.wuffs b/std/gif/decode_gif.wuffs
index 38b8271..50b6bd1 100644
--- a/std/gif/decode_gif.wuffs
+++ b/std/gif/decode_gif.wuffs
@@ -49,25 +49,25 @@
 
 	// Call sequence states:
 	//  - 0: initial state.
-	//  - 1: image config decoded, including the first frame's bounds, but not
+	//  - 3: image config decoded, including the first frame's bounds, but not
 	//       the first frame's pixels.
-	//  - 2: frame config decoded.
-	//  - 3: frame decoded.
+	//  - 4: frame config decoded.
+	//  - 5: frame decoded.
 	//
 	// State transitions:
 	//
-	//  - 0 -> 1: via IC
-	//  - 0 -> 2: via FC with implicit IC
-	//  - 0 -> 3: via F  with implicit IC and FC
+	//  - 0 -> 3: via IC
+	//  - 0 -> 4: via FC with implicit IC
+	//  - 0 -> 5: via F  with implicit IC and FC
 	//
-	//  - 1 -> 2: via FC
-	//  - 1 -> 3: via F  with implicit FC
+	//  - 3 -> 4: via FC
+	//  - 3 -> 5: via F  with implicit FC
 	//
-	//  - 2 -> 2: via FC with implicit F
-	//  - 2 -> 3: via F
+	//  - 4 -> 4: via FC with implicit F
+	//  - 4 -> 5: via F
 	//
-	//  - 3 -> 2: via FC
-	//  - 3 -> 3: via F  with implicit FC
+	//  - 5 -> 4: via FC
+	//  - 5 -> 5: via F  with implicit FC
 	//
 	// Where:
 	//  - F  is decode_frame,        implicit means skip_frame
@@ -130,7 +130,7 @@
 pub func decoder.decode_image_config?(dst nptr base.image_config, src base.io_reader) {
 	var ffio base.bool
 
-	if this.call_sequence >= 1 {
+	if this.call_sequence >= 3 {
 		return base."#bad call sequence"
 	}
 
@@ -158,7 +158,7 @@
 			first_frame_is_opaque:ffio)
 	}
 
-	this.call_sequence = 1
+	this.call_sequence = 3
 }
 
 pub func decoder.num_animation_loops() base.u32 {
@@ -217,8 +217,8 @@
 	if not this.end_of_data {
 		if this.call_sequence == 0 {
 			this.decode_image_config?(dst:nullptr, src:args.src)
-		} else if this.call_sequence <> 1 {
-			if this.call_sequence == 2 {
+		} else if this.call_sequence <> 3 {
+			if this.call_sequence == 4 {
 				this.skip_frame?(src:args.src)
 			}
 			this.decode_up_to_id_part1?(src:args.src)
@@ -250,7 +250,7 @@
 	}
 
 	this.num_decoded_frame_configs_value ~sat+= 1
-	this.call_sequence = 2
+	this.call_sequence = 4
 }
 
 pri func decoder.skip_frame?(src base.io_reader) {
@@ -272,7 +272,7 @@
 
 // TODO: honor args.opts.
 pub func decoder.decode_frame?(dst ptr base.pixel_buffer, src base.io_reader, workbuf slice base.u8, opts nptr base.decode_frame_options) {
-	if this.call_sequence <> 2 {
+	if this.call_sequence <> 4 {
 		this.decode_frame_config?(dst:nullptr, src:args.src)
 	}
 	this.decode_id_part1?(dst:args.dst, src:args.src)
@@ -283,7 +283,7 @@
 }
 
 pri func decoder.reset_gc!() {
-	this.call_sequence = 3
+	this.call_sequence = 5
 	// The Image Descriptor is mandatory, but the Graphic Control extension is
 	// optional. Reset the GC related fields for the next decode_frame call.
 	this.seen_graphic_control = false