diff --git a/apps/treasury/templatetags/escape_tex.py b/apps/treasury/templatetags/escape_tex.py
index 3d635690..c8094ae1 100644
--- a/apps/treasury/templatetags/escape_tex.py
+++ b/apps/treasury/templatetags/escape_tex.py
@@ -16,5 +16,10 @@ def do_latex_escape(value):
     )
 
 
+def fp_value(value):
+    return value.replace("-", "neg ")
+
+
 register = template.Library()
 register.filter("escape_tex", do_latex_escape)
+register.filter("fp_value", fp_value)
diff --git a/templates/treasury/invoice_sample.tex b/templates/treasury/invoice_sample.tex
index 6562e3df..d1b045ac 100644
--- a/templates/treasury/invoice_sample.tex
+++ b/templates/treasury/invoice_sample.tex
@@ -98,7 +98,7 @@
 % Liste des produits facturés : Désignation, quantité, prix unitaire HT
 
 {% for product in products %}
-\AjouterProduit{ {{ product.designation|safe|escape_tex }}} { {{ product.quantity|safe|escape_tex }}} { {{ product.amount_euros|safe|escape_tex }}} { {{ product.total_euros|safe|escape_tex }}}
+\AjouterProduit{ {{ product.designation|safe|escape_tex }}} { {{ product.quantity|safe|escape_tex|fp_value }}} { {{ product.amount_euros|safe|escape_tex|fp_value }}} { {{ product.total_euros|safe|escape_tex|fp_value }}}
 {% endfor %}
 
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%