diff --git a/uhr.js b/uhr.js
index d842352..a2e4e46 100644
--- a/uhr.js
+++ b/uhr.js
@@ -37,6 +37,10 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 			window._uhr.themes.push({'class': styleClass, 'name': name});
 		}
 	}
+	// fall-back if no theme was included
+	if (window._uhr.themes.length == 0) {
+		window._uhr.themes.push({});
+	}
 	$.widget("fritteli.uhr", {
 		options: {
 			width: '100%',
@@ -292,6 +296,19 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 			if (selectedTheme == undefined || this.options.force) {
 				selectedTheme = this.options.theme;
 			}
+			var found = false;
+			for (var i = 0; i < window._uhr.themes.length; i++) {
+				var styleClass = window._uhr.themes[i].class;
+				if (selectedTheme == styleClass) {
+					found = true;
+					break;
+				}
+			}
+			if (!found) {
+				var fallback = window._uhr.themes[0].class;
+				console.warn("Theme " + selectedTheme + " not found! Using fallback: " + fallback);
+				selectedTheme = fallback;
+			}
 			themeChooser.val(selectedTheme);
 			this.options.theme = "";
 			this.theme(selectedTheme);