diff --git a/nix-rust/src/lib.rs b/nix-rust/src/lib.rs
index 48952d8b9..1b88ac8af 100644
--- a/nix-rust/src/lib.rs
+++ b/nix-rust/src/lib.rs
@@ -14,7 +14,6 @@ impl<T> CBox<T> {
         unsafe {
             let size = std::mem::size_of::<T>();
             let ptr = libc::malloc(size);
-            eprintln!("PTR = {:?}, SIZE = {}", ptr, size);
             *(ptr as *mut T) = t; // FIXME: probably UB
             Self {
                 ptr,
diff --git a/src/libstore/builtins/unpack-channel.cc b/src/libstore/builtins/unpack-channel.cc
index 2da26d98e..5fc68cd66 100644
--- a/src/libstore/builtins/unpack-channel.cc
+++ b/src/libstore/builtins/unpack-channel.cc
@@ -1,6 +1,6 @@
-#include "rust.hh"
 #include "builtins.hh"
 #include "compression.hh"
+#include "tarfile.hh"
 
 namespace nix {
 
@@ -27,7 +27,7 @@ void builtinUnpackChannel(const BasicDerivation & drv)
         decompressor->finish();
     });
 
-    unpack_tarfile(*source, out).use()->unwrap();
+    unpackTarfile(*source, out);
 
     auto entries = readDirectory(out);
     if (entries.size() != 1)
diff --git a/src/libstore/local.mk b/src/libstore/local.mk
index d3254554d..d690fea28 100644
--- a/src/libstore/local.mk
+++ b/src/libstore/local.mk
@@ -6,7 +6,7 @@ libstore_DIR := $(d)
 
 libstore_SOURCES := $(wildcard $(d)/*.cc $(d)/builtins/*.cc)
 
-libstore_LIBS = libutil libnixrust
+libstore_LIBS = libutil
 
 libstore_LDFLAGS = $(SQLITE3_LIBS) -lbz2 $(LIBCURL_LIBS) $(SODIUM_LIBS) -pthread
 ifneq ($(OS), FreeBSD)
diff --git a/src/libutil/local.mk b/src/libutil/local.mk
index e41a67d1f..35c1f6c13 100644
--- a/src/libutil/local.mk
+++ b/src/libutil/local.mk
@@ -7,3 +7,5 @@ libutil_DIR := $(d)
 libutil_SOURCES := $(wildcard $(d)/*.cc)
 
 libutil_LDFLAGS = $(LIBLZMA_LIBS) -lbz2 -pthread $(OPENSSL_LIBS) $(LIBBROTLI_LIBS) $(BOOST_LDFLAGS) -lboost_context
+
+libutil_LIBS = libnixrust
diff --git a/src/libutil/rust-ffi.cc b/src/libutil/rust-ffi.cc
index a616d83a6..931d29542 100644
--- a/src/libutil/rust-ffi.cc
+++ b/src/libutil/rust-ffi.cc
@@ -1,5 +1,5 @@
 #include "logging.hh"
-#include "rust.hh"
+#include "rust-ffi.hh"
 
 namespace nix {
 
diff --git a/src/libstore/rust.hh b/src/libutil/tarfile.cc
similarity index 53%
rename from src/libstore/rust.hh
rename to src/libutil/tarfile.cc
index dccc98b4b..ae6d512bd 100644
--- a/src/libstore/rust.hh
+++ b/src/libutil/tarfile.cc
@@ -1,6 +1,14 @@
-#include "serialise.hh"
 #include "rust-ffi.hh"
 
 extern "C" {
     rust::CBox2<rust::Result<std::tuple<>>> unpack_tarfile(rust::Source source, rust::StringSlice dest_dir);
 }
+
+namespace nix {
+
+void unpackTarfile(Source & source, Path destDir)
+{
+    unpack_tarfile(source, destDir).use()->unwrap();
+}
+
+}
diff --git a/src/libutil/tarfile.hh b/src/libutil/tarfile.hh
new file mode 100644
index 000000000..c3e95fb0c
--- /dev/null
+++ b/src/libutil/tarfile.hh
@@ -0,0 +1,7 @@
+#include "serialise.hh"
+
+namespace nix {
+
+void unpackTarfile(Source & source, Path destDir);
+
+}