From 1b576dcb2ed7ec7903b715f37125a955802c9701 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Cl=C3=A9ment=20Walter?= <clement0walter@gmail.com>
Date: Tue, 4 Feb 2025 12:24:44 +0100
Subject: [PATCH 1/2] Overwrite to None if n=0

---
 vm/src/vm/vm_core.rs | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/vm/src/vm/vm_core.rs b/vm/src/vm/vm_core.rs
index c04fd3721e..25b7225265 100644
--- a/vm/src/vm/vm_core.rs
+++ b/vm/src/vm/vm_core.rs
@@ -1119,6 +1119,9 @@ impl VirtualMachine {
             VirtualMachineError,
         > {
             if let Some((ptr, n)) = mod_params {
+                if n == 0 {
+                    return Ok(None);
+                }
                 let mod_builtin = self
                     .builtin_runners
                     .iter()

From 8a6cbb99d610178718c490e2c4b85b3b5fe567c0 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Cl=C3=A9ment=20Walter?= <clement0walter@gmail.com>
Date: Wed, 5 Feb 2025 12:10:29 +0100
Subject: [PATCH 2/2] Update Changelog

---
 CHANGELOG.md | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index be252bc857..1ce5e303a6 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,8 @@
 
 #### Upcoming Changes
 
+* fix: `mod_builtin_fill_memory` raises when `n=0` [#1935](https://github.com/lambdaclass/cairo-vm/pull/1935)
+
 * fix(BREAKING): Fix no trace padding flow in proof mode [#1909](https://github.com/lambdaclass/cairo-vm/pull/1909)
 
 * refactor: Limit ret opcode decodeing to Cairo0's standards. [#1925](https://github.com/lambdaclass/cairo-vm/pull/1925)