diff --git a/Integrals_storage.md b/Integrals_storage.md
index 60c0fd4..8419cf7 100644
--- a/Integrals_storage.md
+++ b/Integrals_storage.md
@@ -20,7 +20,7 @@ The Hash function
 =================
 
 The key is a function that maps the four indices i,j,k,l into a unique 64-bit
-integer, and which returns the same value when then permutation symetry
+integer, and which returns the same value when then permutation symmetry
 operations are applied to the indices. As it is a tiny function, it is written
 in the module that uses it intensively such that it can be inlined by the compiler,
 namely the `Integrals_Bielec/mo_bi_integrals.irp.f` file.