diff --git a/src/io/readers/precursor_reader.rs b/src/io/readers/precursor_reader.rs
index 96c5027..04f0324 100644
--- a/src/io/readers/precursor_reader.rs
+++ b/src/io/readers/precursor_reader.rs
@@ -93,7 +93,7 @@ impl PrecursorReaderBuilder {
     }
 }
 
-trait PrecursorReaderTrait: Sync {
+trait PrecursorReaderTrait: Sync + Send {
     fn get(&self, index: usize) -> Option<Precursor>;
     fn len(&self) -> usize;
 }
diff --git a/src/io/readers/spectrum_reader.rs b/src/io/readers/spectrum_reader.rs
index 9607cb5..5a625f1 100644
--- a/src/io/readers/spectrum_reader.rs
+++ b/src/io/readers/spectrum_reader.rs
@@ -64,7 +64,7 @@ impl SpectrumReader {
         spectra
     }
 
-    pub fn calibrate(&mut self) {
+    fn calibrate(&mut self) {
         self.spectrum_reader.calibrate();
     }
 }
@@ -116,7 +116,7 @@ impl SpectrumReaderBuilder {
     }
 }
 
-trait SpectrumReaderTrait: Sync {
+trait SpectrumReaderTrait: Sync + Send {
     fn get(&self, index: usize) -> Result<Spectrum, SpectrumReaderError>;
     fn get_path(&self) -> PathBuf;
     fn len(&self) -> usize;
diff --git a/src/io/readers/spectrum_reader/tdf/raw_spectra.rs b/src/io/readers/spectrum_reader/tdf/raw_spectra.rs
index 95b4a46..896c759 100644
--- a/src/io/readers/spectrum_reader/tdf/raw_spectra.rs
+++ b/src/io/readers/spectrum_reader/tdf/raw_spectra.rs
@@ -135,7 +135,7 @@ impl RawSpectrumReader {
     }
 }
 
-pub trait RawSpectrumReaderTrait: Sync {
+pub trait RawSpectrumReaderTrait: Sync + Send {
     fn get(&self, index: usize) -> Result<RawSpectrum, RawSpectrumReaderError>;
     fn len(&self) -> usize;
 }