diff --git a/Project.toml b/Project.toml
index 9a8e2cf..a9b2c0b 100644
--- a/Project.toml
+++ b/Project.toml
@@ -21,7 +21,7 @@ HDF5 = "0.15, 0.16"
 ITensors = "0.2"
 Infinities = "0.1"
 IterTools = "1"
-KrylovKit = "0.5"
+KrylovKit = "0.5, 0.6"
 OffsetArrays = "1"
 QuadGK = "2"
 Requires = "1"