diff --git a/poincare/src/expression_lexer.l b/poincare/src/expression_lexer.l
index 7f7f9c9bb..2eb37e35e 100644
--- a/poincare/src/expression_lexer.l
+++ b/poincare/src/expression_lexer.l
@@ -157,6 +157,7 @@ inf { poincare_expression_yylval.expression = new Undefined(); return UNDEFINED;
 \] { return RIGHT_BRACKET; }
 \, { return COMMA; }
 \. { return DOT; }
+[ ]+ /* Ignore whitespaces */
 . { return UNDEFINED_SYMBOL; }
 
 %%