diff --git a/src/utils.rs b/src/utils.rs
index d3841e5..a127bf0 100644
--- a/src/utils.rs
+++ b/src/utils.rs
@@ -34,7 +34,7 @@ pub fn check_files_exist(args: &crate::Cli) {
     } else {
         ".bai"
     };
-    let index = format!("{}.{}", args.bam, index_extension);
+    let index = format!("{}{}", args.bam, index_extension);
     if !Path::new(&index).exists() {
         error!("Index file not found: {}", index);
         std::process::exit(1);
@@ -48,4 +48,4 @@ pub fn check_files_exist(args: &crate::Cli) {
         error!("FASTA index file not found: {}", fai);
         std::process::exit(1);
     }
-}
\ No newline at end of file
+}