diff --git a/pyproject.toml b/pyproject.toml
index 1f1cce84..34514b04 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -22,7 +22,7 @@ base58 = "^2.0.1"
 base91 = "^1.0.1"
 pybase62 = ">=0.4.3,<0.6.0"
 click = ">=7.1.2,<9.0.0"
-mock = "^4.0.3"
+mock = ">=4.0.3,<6.0.0"
 pywhat = "3.0.0"
 xortool-ciphey = "^0.1.16"