diff --git a/Cargo.toml b/Cargo.toml
index 21857e9d8e2..32518b75620 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -76,9 +76,7 @@ lto = "fat"
 panic = 'abort'
 codegen-units = 1
 incremental = false
-
-[profile.release.build-override]
-opt-level = 0
+build-override = { opt-level = 0 }
 
 [workspace]
 members = [
diff --git a/gitoxide-core/src/lib.rs b/gitoxide-core/src/lib.rs
index 4f024436854..a273693d106 100644
--- a/gitoxide-core/src/lib.rs
+++ b/gitoxide-core/src/lib.rs
@@ -1,6 +1,6 @@
 #![forbid(unsafe_code)]
 
-use anyhow::{anyhow, Context, Result};
+use anyhow::{anyhow, Context as AnyhowContext, Result};
 use bytesize::ByteSize;
 use git_features::progress::Progress;
 use git_object::Kind;
@@ -39,20 +39,33 @@ impl FromStr for OutputFormat {
     }
 }
 
+pub struct Context<W1: io::Write, W2: io::Write> {
+    /// If set, provide statistics to `out` in the given format
+    pub output_statistics: Option<OutputFormat>,
+    /// A stream to which to output operation results
+    pub out: W1,
+    /// A stream to which to errors
+    pub err: W2,
+}
+
 pub fn init() -> Result<()> {
     git_repository::init::repository().with_context(|| "Repository initialization failed")
 }
 
-pub fn verify_pack_or_pack_index<P>(
+pub fn verify_pack_or_pack_index<P, W1, W2>(
     path: impl AsRef<Path>,
     progress: Option<P>,
-    output_statistics: Option<OutputFormat>,
-    mut out: impl io::Write,
-    mut err: impl io::Write,
+    Context {
+        mut out,
+        mut err,
+        output_statistics,
+    }: Context<W1, W2>,
 ) -> Result<(git_object::Id, Option<index::PackFileChecksumResult>)>
 where
     P: Progress,
     <P as Progress>::SubProgress: Send,
+    W1: io::Write,
+    W2: io::Write,
 {
     let path = path.as_ref();
     let ext = path.extension().and_then(|ext| ext.to_str()).ok_or_else(|| {
diff --git a/src/plumbing/lean.rs b/src/plumbing/lean.rs
index 749b9a2ac36..965f25db834 100644
--- a/src/plumbing/lean.rs
+++ b/src/plumbing/lean.rs
@@ -79,13 +79,15 @@ pub fn main() -> Result<()> {
             core::verify_pack_or_pack_index(
                 path,
                 progress,
-                if statistics {
-                    Some(core::OutputFormat::Human)
-                } else {
-                    None
+                core::Context {
+                    output_statistics: if statistics {
+                        Some(core::OutputFormat::Human)
+                    } else {
+                        None
+                    },
+                    out: stdout(),
+                    err: stderr(),
                 },
-                stdout(),
-                stderr(),
             )
             .map(|_| ())
         }
diff --git a/src/plumbing/pretty.rs b/src/plumbing/pretty.rs
index 4ad090be317..fa34284b87d 100644
--- a/src/plumbing/pretty.rs
+++ b/src/plumbing/pretty.rs
@@ -161,7 +161,15 @@ pub fn main() -> Result<()> {
             progress,
             progress_keep_open,
             move |progress, out, err| {
-                core::verify_pack_or_pack_index(path, progress, if statistics { Some(format) } else { None }, out, err)
+                core::verify_pack_or_pack_index(
+                    path,
+                    progress,
+                    core::Context {
+                        output_statistics: if statistics { Some(format) } else { None },
+                        out,
+                        err,
+                    },
+                )
             },
         )
         .map(|_| ()),
diff --git a/tests/stateless-journey.sh b/tests/stateless-journey.sh
index 623ff82bb5e..5bca00f890d 100755
--- a/tests/stateless-journey.sh
+++ b/tests/stateless-journey.sh
@@ -65,7 +65,7 @@ title "CLI ${kind}"
       (with "statistics (JSON)"
         it "verifies the pack index successfully and with desired output" && {
           WITH_SNAPSHOT="$snapshot/plumbing-verify-pack-index-with-statistics-json-success" \
-          expect_run $SUCCESSFULLY "$exe_plumbing" verify-pack --statistics --format json "$PACK_INDEX_FILE"
+          expect_run $SUCCESSFULLY "$exe_plumbing" --threads 1 verify-pack --statistics --format json "$PACK_INDEX_FILE"
         }
       )
       fi