diff --git a/src/liblzma/common/alone_decoder.c b/src/liblzma/common/alone_decoder.c
index 5c4d60b1..1dc85bad 100644
--- a/src/liblzma/common/alone_decoder.c
+++ b/src/liblzma/common/alone_decoder.c
@@ -110,12 +110,24 @@ alone_decode(void *coder_ptr, const lzma_allocator *allocator,
 		// Another hack to ditch false positives: Assume that
 		// if the uncompressed size is known, it must be less
 		// than 256 GiB.
+		//
+		// FIXME? Without picky we allow > LZMA_VLI_MAX which doesn't
+		// really matter in this specific situation (> LZMA_VLI_MAX is
+		// safe in the LZMA decoder) but it's somewhat weird still.
 		if (coder->picky
 				&& coder->uncompressed_size != LZMA_VLI_UNKNOWN
 				&& coder->uncompressed_size
 					>= (LZMA_VLI_C(1) << 38))
 			return LZMA_FORMAT_ERROR;
 
+		// Use LZMA_FILTER_LZMA1EXT features to specify the
+		// uncompressed size and that the end marker is allowed
+		// even when the uncompressed size is known. Both .lzma
+		// header and LZMA1EXT use UINT64_MAX indicate that size
+		// is unknown.
+		coder->options.ext_flags = LZMA_LZMA1EXT_ALLOW_EOPM;
+		lzma_set_ext_size(coder->options, coder->uncompressed_size);
+
 		// Calculate the memory usage so that it is ready
 		// for SEQ_CODER_INIT.
 		coder->memusage = lzma_lzma_decoder_memusage(&coder->options)
@@ -132,7 +144,7 @@ alone_decode(void *coder_ptr, const lzma_allocator *allocator,
 
 		lzma_filter_info filters[2] = {
 			{
-				.id = LZMA_FILTER_LZMA1,
+				.id = LZMA_FILTER_LZMA1EXT,
 				.init = &lzma_lzma_decoder_init,
 				.options = &coder->options,
 			}, {
@@ -143,10 +155,6 @@ alone_decode(void *coder_ptr, const lzma_allocator *allocator,
 		return_if_error(lzma_next_filter_init(&coder->next,
 				allocator, filters));
 
-		// Use a hack to set the uncompressed size.
-		lzma_lz_decoder_uncompressed(coder->next.coder,
-				coder->uncompressed_size, true);
-
 		coder->sequence = SEQ_CODE;
 		break;
 	}