diff --git a/Project.toml b/Project.toml
index ec8253a..e9da77d 100644
--- a/Project.toml
+++ b/Project.toml
@@ -12,4 +12,4 @@ JuMP = "4076af6c-e467-56ae-b986-b466b2749572"
 DataFrames = "^1"
 GLPK = "0.6.1 - 1.0.1"
 JuMP = "0.18.3 - 1.1.0"
-julia = "^1.5"
+julia = "^1.4"