diff --git a/Improving-performance-with-Viper-code.md b/Improving-performance-with-Viper-code.md
index 1fa50ad..9809a36 100644
--- a/Improving-performance-with-Viper-code.md
+++ b/Improving-performance-with-Viper-code.md
@@ -136,7 +136,7 @@ As it is usual in Python, a Viper variable is of type Viper `int when  you assig
 ```
 If the variable is created by assigning an expression, the Viper code emitter will evaluate the expression at compile time.
 
-Be aware: Integer expressions outside of what is called the "small integer" range of MicroPython are not Viper `int` but `builtins.int`.  On most architectures a MicroPython small integer falls is -2\*\*29 and 2\*\*29-1. 
+Be aware: Integer constant expressions outside of what is called the "small integer" range of MicroPython are not Viper `int` but `builtins.int`.  On most architectures a MicroPython small integer falls is -2\*\*29 and 2\*\*29-1. 
 
 For example:
 ```py