diff --git a/Project.toml b/Project.toml
index 854771d..40f25da 100644
--- a/Project.toml
+++ b/Project.toml
@@ -1,7 +1,7 @@
 name = "DataDeps"
 uuid = "124859b0-ceae-595e-8997-d05f6a7a8dfe"
 authors = ["Lyndon White <oxinabox@ucc.asn.au>"]
-version = "0.7.7"
+version = "0.7.8"
 
 [deps]
 BinaryProvider = "b99e7846-7c00-51b0-8f62-c81ae34c0232"
diff --git a/src/post_fetch_helpers.jl b/src/post_fetch_helpers.jl
index 979e9ce..c64db33 100644
--- a/src/post_fetch_helpers.jl
+++ b/src/post_fetch_helpers.jl
@@ -4,9 +4,9 @@ function unpack_cmd(file,directory,extension,secondary_extension)
     p7zip() do exe7z
         if secondary_extension == ".tar" || extension == ".tgz" || extension == ".tbz"
             # special handling for compressed tarballs
-            return pipeline(`$exe7z x $file -y -so`, `$exe7z x -si -y -ttar -o$directory`)
+            return pipeline(`$exe7z x $file -y -so`, `$exe7z x -si -y -ttar -o$directory -bso0 -bsp0`)
         else
-            return `$exe7z x $file -y -o$directory`
+            return `$exe7z x $file -y -o$directory -bso0 -bsp0`
         end
     end
 end
diff --git a/test/assets/file1.txt b/test/assets/file1.txt
new file mode 100644
index 0000000..a7f8d9e
--- /dev/null
+++ b/test/assets/file1.txt
@@ -0,0 +1 @@
+bla
diff --git a/test/post_fetch_helpers.jl b/test/post_fetch_helpers.jl
new file mode 100644
index 0000000..1343479
--- /dev/null
+++ b/test/post_fetch_helpers.jl
@@ -0,0 +1,36 @@
+using Test
+using DataDeps: unpack, p7zip
+
+# Runs `f()` and returns what would normally be printed to stdout
+function capture_stdout(f)
+    std = stdout
+    r, w = redirect_stdout()
+    try
+        f()
+    finally
+        redirect_stdout(std)
+        close(w)
+    end
+    output = read(r, String)
+    return output
+end
+
+@testset "unpack" begin
+
+    @testset "happy case" begin
+        # Create dummy zip
+        p7zip() do exe7z
+            run(`$exe7z a assets/test.zip assets/file1.txt -bso0 -bsp0`)
+        end
+
+        output = capture_stdout() do
+            unpack("assets/test.zip")
+        end
+        @test output == ""  # silent
+    end
+
+    @testset "sad case" begin
+        # depending on Julia version may be ErrorException or ProcessFailedException
+        @test_throws Union{ErrorException,ProcessFailedException} unpack("assets/non-existent.zip")
+    end
+end
diff --git a/test/runtests.jl b/test/runtests.jl
index 649475c..f3d7942 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -9,6 +9,7 @@ using Test
         "main",
         "preupload",
         "fetch_helpers",
+        "post_fetch_helpers",
     ]
     @testset "tests" begin
         for filename in tests