diff --git a/api4/file.go b/api4/file.go
index 1a50aff76c..5fe92b49e3 100644
--- a/api4/file.go
+++ b/api4/file.go
@@ -42,6 +42,7 @@ var MEDIA_CONTENT_TYPES = [...]string{
 	"image/png",
 	"image/bmp",
 	"image/gif",
+	"image/tiff",
 	"video/avi",
 	"video/mpeg",
 	"video/mp4",
diff --git a/api4/file_test.go b/api4/file_test.go
index 00b78b39c5..bba7dd8ee3 100644
--- a/api4/file_test.go
+++ b/api4/file_test.go
@@ -346,14 +346,14 @@ func TestUploadFiles(t *testing.T) {
 		// Upload a bunch of files, mixed images and non-images
 		{
 			title:             "Happy",
-			names:             []string{"test.png", "testgif.gif", "testplugin.tar.gz", "test-search.md"},
+			names:             []string{"test.png", "testgif.gif", "testplugin.tar.gz", "test-search.md", "test.tiff"},
 			expectedCreatorId: th.BasicUser.Id,
 		},
 		// Upload a bunch of files, with clientIds
 		{
 			title:             "Happy client_ids",
-			names:             []string{"test.png", "testgif.gif", "testplugin.tar.gz", "test-search.md"},
-			clientIds:         []string{"1", "2", "3", "4"},
+			names:             []string{"test.png", "testgif.gif", "testplugin.tar.gz", "test-search.md", "test.tiff"},
+			clientIds:         []string{"1", "2", "3", "4", "5"},
 			expectedCreatorId: th.BasicUser.Id,
 		},
 		// Upload a bunch of images. testgif.gif is an animated GIF,
@@ -478,6 +478,18 @@ func TestUploadFiles(t *testing.T) {
 			expectedImageHasPreview:     []bool{true},
 			expectedCreatorId:           th.BasicUser.Id,
 		},
+		// TIFF preview test
+		{
+			title:                       "Happy image thumbnail/preview 9",
+			names:                       []string{"test.tiff"},
+			expectedImageThumbnailNames: []string{"test_expected_thumb.tiff"},
+			expectedImagePreviewNames:   []string{"test_expected_preview.tiff"},
+			expectImage:                 true,
+			expectedImageWidths:         []int{701},
+			expectedImageHeights:        []int{701},
+			expectedImageHasPreview:     []bool{true},
+			expectedCreatorId:           th.BasicUser.Id,
+		},
 		{
 			title:             "Happy admin",
 			client:            th.SystemAdminClient,
diff --git a/model/file.go b/model/file.go
index c7ffbf0b9b..e3ee032689 100644
--- a/model/file.go
+++ b/model/file.go
@@ -13,8 +13,8 @@ const (
 )
 
 var (
-	IMAGE_EXTENSIONS = [5]string{".jpg", ".jpeg", ".gif", ".bmp", ".png"}
-	IMAGE_MIME_TYPES = map[string]string{".jpg": "image/jpeg", ".jpeg": "image/jpeg", ".gif": "image/gif", ".bmp": "image/bmp", ".png": "image/png", ".tiff": "image/tiff"}
+	IMAGE_EXTENSIONS = [7]string{".jpg", ".jpeg", ".gif", ".bmp", ".png", ".tiff", "tif"}
+	IMAGE_MIME_TYPES = map[string]string{".jpg": "image/jpeg", ".jpeg": "image/jpeg", ".gif": "image/gif", ".bmp": "image/bmp", ".png": "image/png", ".tiff": "image/tiff", ".tif": "image/tif"}
 )
 
 type FileUploadResponse struct {
diff --git a/tests/test.tiff b/tests/test.tiff
new file mode 100644
index 0000000000..7e8c5fdaab
Binary files /dev/null and b/tests/test.tiff differ
diff --git a/tests/test_expected_preview.tiff b/tests/test_expected_preview.tiff
new file mode 100644
index 0000000000..6972917a42
Binary files /dev/null and b/tests/test_expected_preview.tiff differ
diff --git a/tests/test_expected_thumb.tiff b/tests/test_expected_thumb.tiff
new file mode 100644
index 0000000000..36d4ab758b
Binary files /dev/null and b/tests/test_expected_thumb.tiff differ