--- a/Cargo.toml
+++ b/Cargo.toml
@@ -44,8 +44,10 @@
 [dependencies.chrono]
 version = "0.4"
 
+#note: build will fail if railway-core is built against a different version
+#of chrono-tz.
 [dependencies.chrono-tz]
-version = "0.8.6"
+version = ">= 0.8.6, < 0.11"
 
 [dependencies.rcore]
 version = "0.2"
