diff --git a/ffi.nimble b/ffi.nimble
index 12c9f3a..dc168db 100644
--- a/ffi.nimble
+++ b/ffi.nimble
@@ -11,7 +11,7 @@ requires "nim >= 2.2.4"
 requires "chronos"
 requires "chronicles"
 requires "taskpools"
-requires "cbor_serialization"
+requires "cbor_serialization == 0.3.0"
 
 const nimFlagsOrc = "--mm:orc -d:chronicles_log_level=WARN"
 const nimFlagsRefc = "--mm:refc -d:chronicles_log_level=WARN"