diff --git a/commands.go b/commands.go
index 5f5f8d36f9..cb7b57ff00 100644
--- a/commands.go
+++ b/commands.go
@@ -915,21 +915,21 @@ func (opts AttachOpts) Get(val string) bool {
 }
 
 // PathOpts stores a unique set of absolute paths
-type PathOpts map[string]string
+type PathOpts map[string]struct{}
 
 func NewPathOpts() PathOpts {
 	return make(PathOpts)
 }
 
 func (opts PathOpts) String() string {
-	return fmt.Sprintf("%v", map[string]string(opts))
+	return fmt.Sprintf("%v", map[string]struct{}(opts))
 }
 
 func (opts PathOpts) Set(val string) error {
 	if !filepath.IsAbs(val) {
 		return fmt.Errorf("%s is not an absolute path", val)
 	}
-	opts[filepath.Clean(val)] = ""
+	opts[filepath.Clean(val)] = struct{}{}
 	return nil
 }
 
diff --git a/container.go b/container.go
index 4475fdac40..2edcd6776b 100644
--- a/container.go
+++ b/container.go
@@ -66,7 +66,7 @@ type Config struct {
 	Cmd          []string
 	Dns          []string
 	Image        string // Name of the image as it was passed by the operator (eg. could be symbolic)
-	Volumes      map[string]string
+	Volumes      map[string]struct{}
 }
 
 func ParseRun(args []string, stdout io.Writer, capabilities *Capabilities) (*Config, error) {