diff --git a/lib/includes/nghttp2/nghttp2.h b/lib/includes/nghttp2/nghttp2.h
index 79801520..b370df8e 100644
--- a/lib/includes/nghttp2/nghttp2.h
+++ b/lib/includes/nghttp2/nghttp2.h
@@ -284,10 +284,6 @@ typedef enum {
    * requested operation.
    */
   NGHTTP2_ERR_INVALID_STATE = -519,
-  /**
-   * The gzip error.
-   */
-  NGHTTP2_ERR_GZIP = -520,
   /**
    * The user callback function failed due to the temporal error.
    */
diff --git a/lib/nghttp2_helper.c b/lib/nghttp2_helper.c
index ed177336..51781f28 100644
--- a/lib/nghttp2_helper.c
+++ b/lib/nghttp2_helper.c
@@ -201,8 +201,6 @@ const char* nghttp2_strerror(int error_code)
     return "Invalid header block";
   case NGHTTP2_ERR_INVALID_STATE:
     return "Invalid state";
-  case NGHTTP2_ERR_GZIP:
-    return "Gzip error";
   case NGHTTP2_ERR_TEMPORAL_CALLBACK_FAILURE:
     return "The user callback function failed due to the temporal error";
   case NGHTTP2_ERR_FRAME_SIZE_ERROR:
diff --git a/src/nghttp2_gzip.c b/src/nghttp2_gzip.c
index 9cb8f9a6..d7fc13e0 100644
--- a/src/nghttp2_gzip.c
+++ b/src/nghttp2_gzip.c
@@ -31,7 +31,7 @@ int nghttp2_gzip_inflate_new(nghttp2_gzip **inflater_ptr)
   int rv;
   *inflater_ptr = malloc(sizeof(nghttp2_gzip));
   if(*inflater_ptr == NULL) {
-    return NGHTTP2_ERR_NOMEM;
+    return -1;
   }
   (*inflater_ptr)->finished = 0;
   (*inflater_ptr)->zst.next_in = Z_NULL;
@@ -42,7 +42,7 @@ int nghttp2_gzip_inflate_new(nghttp2_gzip **inflater_ptr)
   rv = inflateInit2(&(*inflater_ptr)->zst, 47);
   if(rv != Z_OK) {
     free(*inflater_ptr);
-    return NGHTTP2_ERR_GZIP;
+    return -1;
   }
   return 0;
 }
@@ -61,7 +61,7 @@ int nghttp2_gzip_inflate(nghttp2_gzip *inflater,
 {
   int rv;
   if(inflater->finished) {
-    return NGHTTP2_ERR_GZIP;
+    return -1;
   }
   inflater->zst.avail_in = *inlen_ptr;
   inflater->zst.next_in = (unsigned char*)in;
@@ -82,7 +82,7 @@ int nghttp2_gzip_inflate(nghttp2_gzip *inflater,
   case Z_STREAM_ERROR:
   case Z_NEED_DICT:
   case Z_MEM_ERROR:
-    return NGHTTP2_ERR_GZIP;
+    return -1;
   default:
     assert(0);
     /* We need this for some compilers */
diff --git a/src/nghttp2_gzip.h b/src/nghttp2_gzip.h
index 26b92d94..9eea35ac 100644
--- a/src/nghttp2_gzip.h
+++ b/src/nghttp2_gzip.h
@@ -51,13 +51,7 @@ typedef struct {
  * A helper function to set up a per request gzip stream to inflate
  * data.
  *
- * This function returns 0 if it succeeds, or one of the following
- * negative error codes:
- *
- * :enum:`NGHTTP2_ERR_GZIP`
- *     The initialization of gzip stream failed.
- * :enum:`NGHTTP2_ERR_NOMEM`
- *     Out of memory.
+ * This function returns 0 if it succeeds, or -1.
  */
 int nghttp2_gzip_inflate_new(nghttp2_gzip **inflater_ptr);
 
@@ -77,11 +71,7 @@ void nghttp2_gzip_inflate_del(nghttp2_gzip *inflater);
  * the number of data written in |out|.  Similarly, |*inlen_ptr| is
  * updated to represent the number of input bytes processed.
  *
- * This function returns 0 if it succeeds, or one of the following
- * negative error codes:
- *
- * :enum:`NGHTTP2_ERR_GZIP`
- *     The inflation of gzip stream failed.
+ * This function returns 0 if it succeeds, or -1.
  *
  * The example follows::
  *