diff --git a/cairo1-run/src/main.rs b/cairo1-run/src/main.rs
index cab63bd142..8b2534be5e 100644
--- a/cairo1-run/src/main.rs
+++ b/cairo1-run/src/main.rs
@@ -222,8 +222,8 @@ fn run(args: impl Iterator<Item = String>) -> Result<Option<String>, Error> {
     };
 
     // Try to parse the file as a sierra program
-    let file = std::fs::read_to_string(&args.filename)?;
-    let sierra_program = match serde_json::from_str(&file) {
+    let file = std::fs::read(&args.filename)?;
+    let sierra_program = match serde_json::from_slice(&file) {
         Ok(program) => program,
         Err(_) => {
             // If it fails, try to compile it as a cairo program