diff --git a/library/sha1.c b/library/sha1.c
index 42f3d6c..8d38950 100644
--- a/library/sha1.c
+++ b/library/sha1.c
@@ -405,7 +405,7 @@
     { "" }
 };
 
-static const int sha1_test_buflen[3] =
+static const size_t sha1_test_buflen[3] =
 {
     3, 56, 1000
 };