diff --git a/examples/webpmux.c b/examples/webpmux.c
index 8f46de2a..6abca107 100644
--- a/examples/webpmux.c
+++ b/examples/webpmux.c
@@ -325,17 +325,13 @@ static int ReadFileToWebPData(const char* const filename,
 }
 
 static int CreateMux(const char* const filename, WebPMux** mux) {
-  WebPMuxState mux_state;
   WebPData bitstream;
-
   assert(mux != NULL);
-
   if (!ReadFileToWebPData(filename, &bitstream)) return 0;
-  *mux = WebPMuxCreate(&bitstream, 1, &mux_state);
+  *mux = WebPMuxCreate(&bitstream, 1);
   free((void*)bitstream.bytes_);
-  if (*mux != NULL && mux_state == WEBP_MUX_STATE_COMPLETE) return 1;
-  fprintf(stderr, "Failed to create mux object from file %s. mux_state = %d.\n",
-          filename, mux_state);
+  if (*mux != NULL) return 1;
+  fprintf(stderr, "Failed to create mux object from file %s.\n", filename);
   return 0;
 }
 
@@ -345,15 +341,12 @@ static int ReadImage(const char* filename,
   WebPMux* mux;
   WebPMuxError err;
   int ok = 0;
-  WebPMuxState mux_state;
 
   if (!ReadFileToWebPData(filename, &bitstream)) return 0;
-  mux = WebPMuxCreate(&bitstream, 1, &mux_state);
+  mux = WebPMuxCreate(&bitstream, 1);
   free((void*)bitstream.bytes_);
-  if (mux == NULL || mux_state != WEBP_MUX_STATE_COMPLETE) {
-    fprintf(stderr,
-            "Failed to create mux object from file %s. mux_state = %d.\n",
-            filename, mux_state);
+  if (mux == NULL) {
+    fprintf(stderr, "Failed to create mux object from file %s.\n", filename);
     return 0;
   }
   err = WebPMuxGetImage(mux, &image, &alpha);
diff --git a/src/mux/muxedit.c b/src/mux/muxedit.c
index 283014b3..74fac063 100644
--- a/src/mux/muxedit.c
+++ b/src/mux/muxedit.c
@@ -23,7 +23,6 @@ extern "C" {
 static void MuxInit(WebPMux* const mux) {
   if (mux == NULL) return;
   memset(mux, 0, sizeof(*mux));
-  mux->state_ = WEBP_MUX_STATE_PARTIAL;
 }
 
 WebPMux* WebPNewInternal(int version) {
@@ -182,11 +181,8 @@ static WebPMuxError GetImageData(const WebPData* const bitstream,
   } else {
     // It is webp file data. Extract image data from it.
     WebPMuxError err;
-    WebPMuxState mux_state;
-    WebPMux* const mux = WebPMuxCreate(bitstream, 0, &mux_state);
-    if (mux == NULL || mux_state != WEBP_MUX_STATE_COMPLETE) {
-      return WEBP_MUX_BAD_DATA;
-    }
+    WebPMux* const mux = WebPMuxCreate(bitstream, 0);
+    if (mux == NULL) return WEBP_MUX_BAD_DATA;
     err = WebPMuxGetImage(mux, image, alpha);
     WebPMuxDelete(mux);
     *is_lossless = VP8LCheckSignature(image->bytes_, image->size_);
@@ -676,9 +672,6 @@ WebPMuxError WebPMuxAssemble(WebPMux* const mux,
   err = CreateVP8XChunk(mux);
   if (err != WEBP_MUX_OK) return err;
 
-  // Mark mux as complete.
-  mux->state_ = WEBP_MUX_STATE_COMPLETE;
-
   // Allocate data.
   size = ChunksListDiskSize(mux->vp8x_) + ChunksListDiskSize(mux->iccp_)
        + ChunksListDiskSize(mux->loop_) + MuxImageListDiskSize(mux->images_)
diff --git a/src/mux/muxi.h b/src/mux/muxi.h
index 37286958..045877f3 100644
--- a/src/mux/muxi.h
+++ b/src/mux/muxi.h
@@ -60,7 +60,6 @@ struct WebPMuxImage {
 
 // Main mux object. Stores data chunks.
 struct WebPMux {
-  WebPMuxState    state_;
   WebPMuxImage*   images_;
   WebPChunk*      iccp_;
   WebPChunk*      meta_;
diff --git a/src/mux/muxinternal.c b/src/mux/muxinternal.c
index 6fefedfd..033628fb 100644
--- a/src/mux/muxinternal.c
+++ b/src/mux/muxinternal.c
@@ -507,12 +507,7 @@ WebPMuxError MuxValidate(const WebPMux* const mux) {
   WebPMuxError err;
 
   // Verify mux is not NULL.
-  if (mux == NULL || mux->state_ == WEBP_MUX_STATE_ERROR) {
-    return WEBP_MUX_INVALID_ARGUMENT;
-  }
-
-  // No further checks if mux is partial.
-  if (mux->state_ == WEBP_MUX_STATE_PARTIAL) return WEBP_MUX_OK;
+  if (mux == NULL) return WEBP_MUX_INVALID_ARGUMENT;
 
   // Verify mux has at least one image.
   if (mux->images_ == NULL) return WEBP_MUX_INVALID_ARGUMENT;
diff --git a/src/mux/muxread.c b/src/mux/muxread.c
index 8504bd66..55375559 100644
--- a/src/mux/muxread.c
+++ b/src/mux/muxread.c
@@ -78,7 +78,7 @@ static WebPMuxError ChunkAssignData(WebPChunk* chunk, const uint8_t* data,
 // Create a mux object from WebP-RIFF data.
 
 WebPMux* WebPMuxCreateInternal(const WebPData* const bitstream, int copy_data,
-                               WebPMuxState* const mux_state, int version) {
+                               int version) {
   size_t riff_size;
   uint32_t tag;
   const uint8_t* end;
@@ -87,8 +87,6 @@ WebPMux* WebPMuxCreateInternal(const WebPData* const bitstream, int copy_data,
   const uint8_t* data;
   size_t size;
 
-  if (mux_state) *mux_state = WEBP_MUX_STATE_PARTIAL;
-
   // Sanity checks.
   if (version != WEBP_MUX_ABI_VERSION) goto Err;  // version mismatch
   if (bitstream == NULL) goto Err;
@@ -106,10 +104,7 @@ WebPMux* WebPMuxCreateInternal(const WebPData* const bitstream, int copy_data,
   mux = WebPMuxNew();
   if (mux == NULL) goto Err;
 
-  if (size < RIFF_HEADER_SIZE + TAG_SIZE) {
-    mux->state_ = WEBP_MUX_STATE_PARTIAL;
-    goto Ok;
-  }
+  if (size < RIFF_HEADER_SIZE + TAG_SIZE) goto Err;
 
   tag = GetLE32(data + RIFF_HEADER_SIZE);
   if (tag != kChunks[IDX_VP8].tag &&
@@ -119,12 +114,9 @@ WebPMux* WebPMuxCreateInternal(const WebPData* const bitstream, int copy_data,
   }
 
   riff_size = SizeWithPadding(GetLE32(data + TAG_SIZE));
-  if (riff_size > MAX_CHUNK_PAYLOAD) {
+  if (riff_size > MAX_CHUNK_PAYLOAD || riff_size > size) {
     goto Err;
-  } else if (riff_size > size) {
-    mux->state_ = WEBP_MUX_STATE_PARTIAL;
   } else {
-    mux->state_ = WEBP_MUX_STATE_COMPLETE;
     if (riff_size < size) {  // Redundant data after last chunk.
       size = riff_size;  // To make sure we don't read any data beyond mux_size.
     }
@@ -146,14 +138,7 @@ WebPMux* WebPMuxCreateInternal(const WebPData* const bitstream, int copy_data,
 
     ChunkInit(&chunk);
     err = ChunkAssignData(&chunk, data, size, riff_size, copy_data);
-    if (err != WEBP_MUX_OK) {
-      if (err == WEBP_MUX_NOT_ENOUGH_DATA &&
-          mux->state_ == WEBP_MUX_STATE_PARTIAL) {
-        goto Ok;
-      } else {
-        goto Err;
-      }
-    }
+    if (err != WEBP_MUX_OK) goto Err;
 
     id = ChunkGetIdFromTag(chunk.tag_);
 
@@ -191,15 +176,12 @@ WebPMux* WebPMuxCreateInternal(const WebPData* const bitstream, int copy_data,
   // Validate mux if complete.
   if (MuxValidate(mux) != WEBP_MUX_OK) goto Err;
 
- Ok:
   MuxImageDelete(wpi);
-  if (mux_state) *mux_state = mux->state_;
   return mux;  // All OK;
 
  Err:  // Something bad happened.
   MuxImageDelete(wpi);
   WebPMuxDelete(mux);
-  if (mux_state) *mux_state = WEBP_MUX_STATE_ERROR;
   return NULL;
 }
 
@@ -217,13 +199,7 @@ WebPMuxError WebPMuxGetFeatures(const WebPMux* const mux, uint32_t* flags) {
   err = MuxGet(mux, IDX_VP8X, 1, &data);
   if (err == WEBP_MUX_NOT_FOUND) {
     // Check if VP8/VP8L chunk is present.
-    err = WebPMuxGetImage(mux, &data, NULL);
-    if (err == WEBP_MUX_NOT_FOUND &&              // Data not available (yet).
-        mux->state_ == WEBP_MUX_STATE_PARTIAL) {  // Incremental case.
-      return WEBP_MUX_NOT_ENOUGH_DATA;
-    } else {
-      return err;
-    }
+    return WebPMuxGetImage(mux, &data, NULL);
   } else if (err != WEBP_MUX_OK) {
     return err;
   }
diff --git a/src/webp/mux.h b/src/webp/mux.h
index aa589411..0aff297c 100644
--- a/src/webp/mux.h
+++ b/src/webp/mux.h
@@ -33,7 +33,7 @@
 //
 //   int copy_data = 0;
 //   // ... (Read data from file).
-//   WebPMux* mux = WebPMuxCreate(&data, copy_data, NULL);
+//   WebPMux* mux = WebPMuxCreate(&data, copy_data);
 //   WebPMuxGetImage(mux, &image, &alpha);
 //   // ... (Consume image; e.g. call WebPDecode() to decode the data).
 //   WebPMuxGetColorProfile(mux, &icc_profile);
@@ -64,12 +64,6 @@ typedef enum {
   WEBP_MUX_NOT_ENOUGH_DATA    = -6
 } WebPMuxError;
 
-typedef enum {
-  WEBP_MUX_STATE_PARTIAL  =  0,
-  WEBP_MUX_STATE_COMPLETE =  1,
-  WEBP_MUX_STATE_ERROR    = -1
-} WebPMuxState;
-
 // Flag values for different features used in VP8X chunk.
 typedef enum {
   TILE_FLAG       = 0x00000001,
@@ -117,24 +111,19 @@ WEBP_EXTERN(void) WebPMuxDelete(WebPMux* const mux);
 // Mux creation.
 
 // Internal, version-checked, entry point
-WEBP_EXTERN(WebPMux*) WebPMuxCreateInternal(const WebPData* const,
-                                            int, WebPMuxState* const, int);
+WEBP_EXTERN(WebPMux*) WebPMuxCreateInternal(const WebPData* const, int, int);
 
 // Creates a mux object from raw data given in WebP RIFF format.
 // Parameters:
 //   bitstream - (in) the bitstream data in WebP RIFF format
 //   copy_data - (in) value 1 indicates given data WILL copied to the mux, and
 //               value 0 indicates data will NOT be copied.
-//   mux_state - (out) indicates the state of the mux returned. Can be passed
-//               NULL if not required.
 // Returns:
 //   A pointer to the mux object created from given data - on success.
 //   NULL - In case of invalid data or memory error.
 static WEBP_INLINE WebPMux* WebPMuxCreate(const WebPData* const bitstream,
-                                          int copy_data,
-                                          WebPMuxState* const mux_state) {
-  return WebPMuxCreateInternal(
-      bitstream, copy_data, mux_state, WEBP_MUX_ABI_VERSION);
+                                          int copy_data) {
+  return WebPMuxCreateInternal(bitstream, copy_data, WEBP_MUX_ABI_VERSION);
 }
 
 //------------------------------------------------------------------------------