diff --git a/Cargo.toml b/Cargo.toml
index 892533e..4d2462c 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -22,7 +22,7 @@ num-integer = "0.1"
 num-traits = "0.2"
 rand = "0.8.3"
 itertools = { version = "0.10.0", default-features = false }
-indexmap = "1.6.2"
+indexmap = ">=1"
 
 [dev-dependencies]
 ndarray = { version = "0.15.0", features = ["approx"] }