diff --git a/doc/cs_registers.rst b/doc/cs_registers.rst
index 7ba8c6a9..e8566c3d 100644
--- a/doc/cs_registers.rst
+++ b/doc/cs_registers.rst
@@ -91,7 +91,7 @@ Machine ISA Register (misa)
 CSR Address: ``0x301``
 
 ``misa`` is a WARL register which describes the ISA supported by the hart.
-One Ibex, ``misa`` is hard-wired, i.e. it will remain unchanged after any write.
+On Ibex, ``misa`` is hard-wired, i.e. it will remain unchanged after any write.
 
 
 Machine Trap-Vector Base Address (mtvec)