diff --git a/INSTALL.rst b/INSTALL.rst
index 096199b7510e052cd9026ec71a475e2c815aeaae..b1c752b21a33bd00b04307160286ef4cf4422b00 100644
--- a/INSTALL.rst
+++ b/INSTALL.rst
@@ -420,7 +420,7 @@ Build configuration
 ===================
 
 The setup script of Kwant has to know how to link against LAPACK & BLAS, and,
-optionally, MUMPS.  Be default it will assume that LAPACK and BLAS can be found
+optionally, MUMPS.  By default it will assume that LAPACK and BLAS can be found
 under their usual names.  MUMPS will be not linked against by default, except
 on Debian-based systems when the package ``libmumps-scotch-dev`` is installed.