diff --git a/src/liblzma/common/file_info.c b/src/liblzma/common/file_info.c
index 4b2eb5d0..c14a2819 100644
--- a/src/liblzma/common/file_info.c
+++ b/src/liblzma/common/file_info.c
@@ -717,6 +717,13 @@ file_info_decoder_memconfig(void *coder_ptr, uint64_t *memusage,
 		}
 	}
 
+	// combined_index_memusage + this_index_memusage shouldn't overflow
+	// because combined_index_memusage is limited by how much can be
+	// successfully allocated, and this_index_memusage is limited by
+	// INDEX_RECORDS_MAX in index_decoder.c. Check for overflow anyway.
+	if (UINT64_MAX - combined_index_memusage < this_index_memusage)
+		return LZMA_PROG_ERROR;
+
 	// Now we know the total memory usage/requirement. If we had neither
 	// old Indexes nor a new Index, this will be zero which isn't
 	// acceptable as lzma_memusage() has to return non-zero on success