diff --git a/opensmtpd/Cargo.toml b/opensmtpd/Cargo.toml
index bb994ce..ade22e4 100644
--- a/opensmtpd/Cargo.toml
+++ b/opensmtpd/Cargo.toml
@@ -18,7 +18,7 @@ opensmtpd_derive = { version = "0.4", path = "../opensmtpd-derive" }
 pretty-hex = "0.2"
 
 [dev-dependencies]
-simplelog = "0.9"
+simplelog = "0.10"
 
 [[example]]
 name = "counter"