diff --git a/src/liblzma/api/lzma/block.h b/src/liblzma/api/lzma/block.h
index 2e982e1..7bdcfd7 100644
--- a/src/liblzma/api/lzma/block.h
+++ b/src/liblzma/api/lzma/block.h
@@ -31,11 +31,16 @@
 	/**
 	 * \brief       Block format version
 	 *
-	 * To prevent API and ABI breakages if new features are needed in
-	 * the Block field, a version number is used to indicate which
-	 * fields in this structure are in use. For now, version must always
-	 * be zero. With non-zero version, most Block related functions will
-	 * return LZMA_OPTIONS_ERROR.
+	 * To prevent API and ABI breakages when new features are needed,
+	 * a version number is used to indicate which fields in this
+	 * structure are in use:
+	 *   - liblzma >= 5.0.0: version = 0 is supported.
+	 *   - liblzma >= 5.1.4beta: Support for version = 1 was added,
+	 *     which adds the ignore_check field.
+	 *
+	 * If version is greater than one, most Block related functions
+	 * will return LZMA_OPTIONS_ERROR (lzma_block_header_decode() works
+	 * with any version value).
 	 *
 	 * Read by:
 	 *  - All functions that take pointer to lzma_block as argument,
@@ -233,7 +238,28 @@
 	lzma_reserved_enum reserved_enum2;
 	lzma_reserved_enum reserved_enum3;
 	lzma_reserved_enum reserved_enum4;
-	lzma_bool reserved_bool1;
+
+	/**
+	 * \brief       A flag to Block decoder to not verify the Check field
+	 *
+	 * This field is supported by liblzma >= 5.1.4beta if .version >= 1.
+	 *
+	 * If this is set to true, the integrity check won't be calculated
+	 * and verified. Unless you know what you are doing, you should
+	 * leave this to false. (A reason to set this to true is when the
+	 * file integrity is verified externally anyway and you want to
+	 * speed up the decompression, which matters mostly when using
+	 * SHA-256 as the integrity check.)
+	 *
+	 * If .version >= 1, read by:
+	 *   - lzma_block_decoder()
+	 *   - lzma_block_buffer_decode()
+	 *
+	 * Written by (.version is ignored):
+	 *   - lzma_block_header_decode() always sets this to false
+	 */
+	lzma_bool ignore_check;
+
 	lzma_bool reserved_bool2;
 	lzma_bool reserved_bool3;
 	lzma_bool reserved_bool4;
@@ -310,10 +336,14 @@
 /**
  * \brief       Decode Block Header
  *
- * block->version should be set to the highest value supported by the
- * application; currently the only possible version is zero. This function
- * will set version to the lowest value that still supports all the features
- * required by the Block Header.
+ * block->version should (usually) be set to the highest value supported
+ * by the application. If the application sets block->version to a value
+ * higher than supported by the current liblzma version, this function will
+ * downgrade block->version to the highest value supported by it. Thus one
+ * should check the value of block->version after calling this function if
+ * block->version was set to a non-zero value and the application doesn't
+ * otherwise know that the liblzma version being used is new enough to
+ * support the specified block->version.
  *
  * The size of the Block Header must have already been decoded with
  * lzma_block_header_size_decode() macro and stored to block->header_size.
diff --git a/src/liblzma/common/block_buffer_encoder.c b/src/liblzma/common/block_buffer_encoder.c
index dcd574e..39e263a 100644
--- a/src/liblzma/common/block_buffer_encoder.c
+++ b/src/liblzma/common/block_buffer_encoder.c
@@ -233,7 +233,7 @@
 
 	// The contents of the structure may depend on the version so
 	// check the version before validating the contents of *block.
-	if (block->version != 0)
+	if (block->version > 1)
 		return LZMA_OPTIONS_ERROR;
 
 	if ((unsigned int)(block->check) > LZMA_CHECK_ID_MAX
diff --git a/src/liblzma/common/block_decoder.c b/src/liblzma/common/block_decoder.c
index cee6c78..685c3b0 100644
--- a/src/liblzma/common/block_decoder.c
+++ b/src/liblzma/common/block_decoder.c
@@ -45,6 +45,9 @@
 
 	/// Check of the uncompressed data
 	lzma_check_state check;
+
+	/// True if the integrity check won't be calculated and verified.
+	bool ignore_check;
 };
 
 
@@ -97,8 +100,9 @@
 					coder->block->uncompressed_size))
 			return LZMA_DATA_ERROR;
 
-		lzma_check_update(&coder->check, coder->block->check,
-				out + out_start, out_used);
+		if (!coder->ignore_check)
+			lzma_check_update(&coder->check, coder->block->check,
+					out + out_start, out_used);
 
 		if (ret != LZMA_STREAM_END)
 			return ret;
@@ -140,7 +144,9 @@
 		if (coder->block->check == LZMA_CHECK_NONE)
 			return LZMA_STREAM_END;
 
-		lzma_check_finish(&coder->check, coder->block->check);
+		if (!coder->ignore_check)
+			lzma_check_finish(&coder->check, coder->block->check);
+
 		coder->sequence = SEQ_CHECK;
 
 	// Fall through
@@ -155,7 +161,8 @@
 		// Validate the Check only if we support it.
 		// coder->check.buffer may be uninitialized
 		// when the Check ID is not supported.
-		if (lzma_check_is_supported(coder->block->check)
+		if (!coder->ignore_check
+				&& lzma_check_is_supported(coder->block->check)
 				&& memcmp(coder->block->raw_check,
 					coder->check.buffer.u8,
 					check_size) != 0)
@@ -224,6 +231,9 @@
 	next->coder->check_pos = 0;
 	lzma_check_init(&next->coder->check, block->check);
 
+	next->coder->ignore_check = block->version >= 1
+			? block->ignore_check : false;
+
 	// Initialize the filter chain.
 	return lzma_raw_decoder_init(&next->coder->next, allocator,
 			block->filters);
diff --git a/src/liblzma/common/block_encoder.c b/src/liblzma/common/block_encoder.c
index 15f55f7..def5864 100644
--- a/src/liblzma/common/block_encoder.c
+++ b/src/liblzma/common/block_encoder.c
@@ -166,7 +166,7 @@
 
 	// The contents of the structure may depend on the version so
 	// check the version first.
-	if (block->version != 0)
+	if (block->version > 1)
 		return LZMA_OPTIONS_ERROR;
 
 	// If the Check ID is not supported, we cannot calculate the check and
diff --git a/src/liblzma/common/block_header_decoder.c b/src/liblzma/common/block_header_decoder.c
index 416642c..1dd982f 100644
--- a/src/liblzma/common/block_header_decoder.c
+++ b/src/liblzma/common/block_header_decoder.c
@@ -46,8 +46,16 @@
 		block->filters[i].options = NULL;
 	}
 
-	// Always zero for now.
-	block->version = 0;
+	// Versions 0 and 1 are supported. If a newer version was specified,
+	// we need to downgrade it.
+	if (block->version > 1)
+		block->version = 1;
+
+	// This isn't a Block Header option, but since the decompressor will
+	// read it if version >= 1, it's better to initialize it here than
+	// to expect the caller to do it since in almost all cases this
+	// should be false.
+	block->ignore_check = false;
 
 	// Validate Block Header Size and Check type. The caller must have
 	// already set these, so it is a programming error if this test fails.
diff --git a/src/liblzma/common/block_header_encoder.c b/src/liblzma/common/block_header_encoder.c
index 707dd0c..5c5f542 100644
--- a/src/liblzma/common/block_header_encoder.c
+++ b/src/liblzma/common/block_header_encoder.c
@@ -17,7 +17,7 @@
 extern LZMA_API(lzma_ret)
 lzma_block_header_size(lzma_block *block)
 {
-	if (block->version != 0)
+	if (block->version > 1)
 		return LZMA_OPTIONS_ERROR;
 
 	// Block Header Size + Block Flags + CRC32.
diff --git a/src/liblzma/common/block_util.c b/src/liblzma/common/block_util.c
index 62c9345..00c7fe8 100644
--- a/src/liblzma/common/block_util.c
+++ b/src/liblzma/common/block_util.c
@@ -51,7 +51,7 @@
 	// NOTE: This function is used for validation too, so it is
 	// essential that these checks are always done even if
 	// Compressed Size is unknown.
-	if (block == NULL || block->version != 0
+	if (block == NULL || block->version > 1
 			|| block->header_size < LZMA_BLOCK_HEADER_SIZE_MIN
 			|| block->header_size > LZMA_BLOCK_HEADER_SIZE_MAX
 			|| (block->header_size & 3)