diff --git a/client/allocdir/alloc_dir.go b/client/allocdir/alloc_dir.go
index 08c979471..ac57def65 100644
--- a/client/allocdir/alloc_dir.go
+++ b/client/allocdir/alloc_dir.go
@@ -410,7 +410,7 @@ func (d *AllocDir) Stat(path string) (*cstructs.AllocFileInfo, error) {
 // detectContentType tries to infer the file type by reading the first
 // 512 bytes of the file. Json file extensions are special cased.
 func detectContentType(fileInfo os.FileInfo, path string) string {
-	contentType := "unknown"
+	contentType := "application/octet-stream"
 	if !fileInfo.IsDir() {
 		f, err := os.Open(path)
 		// Best effort content type detection
diff --git a/client/allocdir/alloc_dir_test.go b/client/allocdir/alloc_dir_test.go
index e7103cc58..451ae32e6 100644
--- a/client/allocdir/alloc_dir_test.go
+++ b/client/allocdir/alloc_dir_test.go
@@ -475,15 +475,28 @@ func TestPathFuncs(t *testing.T) {
 
 func TestAllocDir_DetectContentType(t *testing.T) {
 	require := require.New(t)
-	imgPath := "input/image.png"
-	fileInfo, err := os.Stat(imgPath)
+	inputPath := "input/"
+	var testFiles []string
+	err := filepath.Walk(inputPath, func(path string, info os.FileInfo, err error) error {
+		if !info.IsDir() {
+			testFiles = append(testFiles, path)
+		}
+		return err
+	})
 	require.Nil(err)
-	res := detectContentType(fileInfo, imgPath)
-	require.Equal("image/png", res)
 
-	jsonPath := "input/test.json"
-	fileInfo, err = os.Stat(jsonPath)
-	require.Nil(err)
-	res = detectContentType(fileInfo, jsonPath)
-	require.Equal("application/json", res)
+	expectedEncodings := map[string]string{
+		"input/happy.gif": "image/gif",
+		"input/image.png": "image/png",
+		"input/nomad.jpg": "image/jpeg",
+		"input/test.go":   "application/octet-stream",
+		"input/test.json": "application/json",
+		"input/test.txt":  "text/plain; charset=utf-8",
+	}
+	for _, file := range testFiles {
+		fileInfo, err := os.Stat(file)
+		require.Nil(err)
+		res := detectContentType(fileInfo, file)
+		require.Equal(expectedEncodings[file], res)
+	}
 }
diff --git a/client/allocdir/input/happy.gif b/client/allocdir/input/happy.gif
new file mode 100644
index 000000000..13aa264ce
Binary files /dev/null and b/client/allocdir/input/happy.gif differ
diff --git a/client/allocdir/input/nomad.jpg b/client/allocdir/input/nomad.jpg
new file mode 100644
index 000000000..f07871e2e
Binary files /dev/null and b/client/allocdir/input/nomad.jpg differ
diff --git a/client/allocdir/input/test.go b/client/allocdir/input/test.go
new file mode 100644
index 000000000..8fd43ed1e
--- /dev/null
+++ b/client/allocdir/input/test.go
@@ -0,0 +1,9 @@
+package main
+
+import (
+	"fmt"
+)
+
+func main() {
+	fmt.Println("Hello, playground")
+}
diff --git a/client/allocdir/input/test.txt b/client/allocdir/input/test.txt
new file mode 100644
index 000000000..c638ce611
--- /dev/null
+++ b/client/allocdir/input/test.txt
@@ -0,0 +1 @@
+hello world