diff --git a/lib/lzma/LzmaTools.c b/lib/lzma/LzmaTools.c
index 521258e623..af88900d31 100644
--- a/lib/lzma/LzmaTools.c
+++ b/lib/lzma/LzmaTools.c
@@ -37,8 +37,8 @@
 static void *SzAlloc(void *p, size_t size) { return malloc(size); }
 static void SzFree(void *p, void *address) { free(address); }
 
-int lzmaBuffToBuffDecompress (unsigned char *outStream, SizeT *uncompressedSize,
-                  unsigned char *inStream,  SizeT  length)
+int lzmaBuffToBuffDecompress(unsigned char *outStream, SizeT *uncompressedSize,
+			     const unsigned char *inStream, SizeT length)
 {
     int res = SZ_ERROR_DATA;
     int i;
diff --git a/lib/lzma/LzmaTools.h b/lib/lzma/LzmaTools.h
index e52dfb8fac..2c46859a62 100644
--- a/lib/lzma/LzmaTools.h
+++ b/lib/lzma/LzmaTools.h
@@ -13,6 +13,19 @@
 
 #include <lzma/LzmaTypes.h>
 
-extern int lzmaBuffToBuffDecompress (unsigned char *outStream, SizeT *uncompressedSize,
-			      unsigned char *inStream,  SizeT  length);
+/**
+ * lzmaBuffToBuffDecompress() - Decompress LZMA data
+ *
+ * @outStream: output buffer
+ * @uncompressedSize: On entry, the mnaximum uncompressed size of the data;
+ *	on exit, the actual uncompressed size after processing
+ * @inStream: Compressed bytes to decompress
+ * @length: Sizeof @inStream
+ * @return 0 if OK, SZ_ERROR_DATA if the data is in a format that cannot be
+ *	decompressed; SZ_ERROR_OUTPUT_EOF if *uncompressedSize is too small;
+ *	see also other SZ_ERROR... values
+ */
+int lzmaBuffToBuffDecompress(unsigned char *outStream, SizeT *uncompressedSize,
+			     const unsigned char *inStream, SizeT length);
+
 #endif