diff --git a/src/cargo/sources/registry/mod.rs b/src/cargo/sources/registry/mod.rs
index c9c414e50..0c52d530e 100644
--- a/src/cargo/sources/registry/mod.rs
+++ b/src/cargo/sources/registry/mod.rs
@@ -618,7 +618,7 @@ impl<'cfg> RegistrySource<'cfg> {
             }
         }
         let gz = GzDecoder::new(tarball);
-        let gz = LimitErrorReader::new(gz, MAX_UNPACK_SIZE);
+        let gz = LimitErrorReader::new(gz, max_unpack_size());
         let mut tar = Archive::new(gz);
         let prefix = unpack_dir.file_name().unwrap();
         let parent = unpack_dir.parent().unwrap();
@@ -835,6 +835,20 @@ impl<'cfg> Source for RegistrySource<'cfg> {
     }
 }
 
+/// For integration test only.
+#[inline]
+fn max_unpack_size() -> u64 {
+    const VAR: &str = "__CARGO_TEST_MAX_UNPACK_SIZE";
+    if cfg!(debug_assertions) && std::env::var(VAR).is_ok() {
+        std::env::var(VAR)
+            .unwrap()
+            .parse()
+            .expect("a max unpack size in bytes")
+    } else {
+        MAX_UNPACK_SIZE
+    }
+}
+
 fn make_dep_prefix(name: &str) -> String {
     match name.len() {
         1 => String::from("1"),
diff --git a/src/cargo/util/io.rs b/src/cargo/util/io.rs
index f62672db0..60f3ffe05 100644
--- a/src/cargo/util/io.rs
+++ b/src/cargo/util/io.rs
@@ -25,3 +25,27 @@ impl<R: Read> Read for LimitErrorReader<R> {
     }
 }
 
+#[cfg(test)]
+mod tests {
+    use super::LimitErrorReader;
+
+    use std::io::Read;
+
+    #[test]
+    fn under_the_limit() {
+        let buf = &[1; 7][..];
+        let mut r = LimitErrorReader::new(buf, 8);
+        let mut out = Vec::new();
+        assert!(matches!(r.read_to_end(&mut out), Ok(7)));
+        assert_eq!(buf, out.as_slice());
+    }
+
+    #[test]
+    #[should_panic = "maximum limit reached when reading"]
+    fn over_the_limit() {
+        let buf = &[1; 8][..];
+        let mut r = LimitErrorReader::new(buf, 8);
+        let mut out = Vec::new();
+        r.read_to_end(&mut out).unwrap();
+    }
+}
diff --git a/tests/testsuite/registry.rs b/tests/testsuite/registry.rs
index 4fcc4ffbe..a5032d2ac 100644
--- a/tests/testsuite/registry.rs
+++ b/tests/testsuite/registry.rs
@@ -2697,3 +2697,45 @@ fn http_requires_trailing_slash() {
         .with_stderr("[ERROR] registry url must end in a slash `/`: sparse+https://index.crates.io")
         .run()
 }
+
+#[cargo_test]
+fn reach_max_unpack_size() {
+    let p = project()
+        .file(
+            "Cargo.toml",
+            r#"
+                [project]
+                name = "foo"
+                version = "0.0.1"
+
+                [dependencies]
+                bar = ">= 0.0.0"
+            "#,
+        )
+        .file("src/main.rs", "fn main() {}")
+        .build();
+
+    Package::new("bar", "0.0.1").publish();
+
+    p.cargo("build")
+        .env("__CARGO_TEST_MAX_UNPACK_SIZE", "8") // hit 8 bytes limit and boom!
+        .with_status(101)
+        .with_stderr(
+            "\
+[UPDATING] `dummy-registry` index
+[DOWNLOADING] crates ...
+[DOWNLOADED] bar v0.0.1 (registry `dummy-registry`)
+[ERROR] failed to download replaced source registry `crates-io`
+
+Caused by:
+  failed to unpack package `bar v0.0.1 (registry `dummy-registry`)`
+
+Caused by:
+  failed to iterate over archive
+
+Caused by:
+  maximum limit reached when reading
+",
+        )
+        .run();
+}