diff --git a/internal/store/store.go b/internal/store/store.go
index 84283da36..2e04b884a 100644
--- a/internal/store/store.go
+++ b/internal/store/store.go
@@ -46,9 +46,14 @@ func (s *store) Namespace() string {
 }
 
 func (s *store) check(filename string) error {
-	if filename[:len(s.namespace)+1] != s.namespace+"/" {
-		return errors.Errorf("Invalid namespace when trying to store file: %s (for %s)", filename, s.namespace)
+	if len(filename) == 0 {
+		return errors.Errorf("Invalid filename when trying to store file: '%s' (for %s)", filename, s.namespace)
 	}
+
+	if filename[:len(s.namespace)+1] != s.namespace+"/" {
+		return errors.Errorf("Invalid namespace when trying to store file: '%s' (for %s)", filename, s.namespace)
+	}
+
 	return nil
 }
 
diff --git a/internal/store/store_test.go b/internal/store/store_test.go
index 838cac17f..7147ab15c 100644
--- a/internal/store/store_test.go
+++ b/internal/store/store_test.go
@@ -68,3 +68,14 @@ func TestStore(t *testing.T) {
 		assert(err != nil, "Expected error when deleting file outside of namespace")
 	}
 }
+
+func TestStoreCheckFunc(t *testing.T) {
+	assert := func(ok bool, format string, params ...interface{}) {
+		if !ok {
+			t.Fatalf(format, params...)
+		}
+	}
+
+	// Should not cause panic
+	assert((&store{}).check("") != nil, "Expecting an error to be returned on empty filename check")
+}
diff --git a/sam/rest/attachment.go b/sam/rest/attachment.go
index ea833832e..f05a52730 100644
--- a/sam/rest/attachment.go
+++ b/sam/rest/attachment.go
@@ -77,3 +77,7 @@ func (f *file) ModTime() time.Time {
 func (f *file) Content() io.ReadSeeker {
 	return f.content
 }
+
+func (f *file) Valid() bool {
+	return f.content != nil
+}
diff --git a/sam/rest/handlers/attachment_custom.go b/sam/rest/handlers/attachment_custom.go
index 9fd84606e..395eb86b2 100644
--- a/sam/rest/handlers/attachment_custom.go
+++ b/sam/rest/handlers/attachment_custom.go
@@ -1,12 +1,12 @@
 package handlers
 
 import (
-	"net/http"
-
-	"github.com/crusttech/crust/sam/rest/request"
 	"io"
+	"net/http"
 	"net/url"
 	"time"
+
+	"github.com/crusttech/crust/sam/rest/request"
 )
 
 // HTTP API interface
@@ -20,6 +20,7 @@ type Downloadable interface {
 	Download() bool
 	ModTime() time.Time
 	Content() io.ReadSeeker
+	Valid() bool
 }
 
 func NewAttachmentDownloadable(ah AttachmentAPI) *Attachment {
@@ -32,11 +33,15 @@ func NewAttachmentDownloadable(ah AttachmentAPI) *Attachment {
 				http.Error(w, err.Error(), http.StatusInternalServerError)
 			}
 		} else if dl, ok := f.(Downloadable); ok {
-			if dl.Download() {
-				w.Header().Add("Content-Disposition", "attachment; filename="+url.QueryEscape(dl.Name()))
-			}
+			if !dl.Valid() {
+				w.WriteHeader(http.StatusNotFound)
+			} else {
+				if dl.Download() {
+					w.Header().Add("Content-Disposition", "attachment; filename="+url.QueryEscape(dl.Name()))
+				}
 
-			http.ServeContent(w, r, dl.Name(), dl.ModTime(), dl.Content())
+				http.ServeContent(w, r, dl.Name(), dl.ModTime(), dl.Content())
+			}
 		} else {
 			http.Error(w, "Got incompatible type from controller", http.StatusInternalServerError)
 		}
diff --git a/sam/service/attachment.go b/sam/service/attachment.go
index ad4fdeb78..95e36bbe7 100644
--- a/sam/service/attachment.go
+++ b/sam/service/attachment.go
@@ -67,10 +67,18 @@ func (svc *attachment) FindByID(id uint64) (*types.Attachment, error) {
 }
 
 func (svc *attachment) OpenOriginal(att *types.Attachment) (io.ReadSeeker, error) {
+	if len(att.Url) == 0 {
+		return nil, nil
+	}
+
 	return svc.store.Open(att.Url)
 }
 
 func (svc *attachment) OpenPreview(att *types.Attachment) (io.ReadSeeker, error) {
+	if len(att.PreviewUrl) == 0 {
+		return nil, nil
+	}
+
 	return svc.store.Open(att.PreviewUrl)
 }