diff --git a/mozc-nazoru/bin/nazoru-input b/mozc-nazoru/bin/nazoru-input
index 99839f5..9fc0418 100755
--- a/mozc-nazoru/bin/nazoru-input
+++ b/mozc-nazoru/bin/nazoru-input
@@ -16,6 +16,12 @@
 # limitations under the License.
 
 from __future__ import print_function
+
+# Surpress warnings. Please unvail these warnings when development.
+import warnings
+warnings.filterwarnings("ignore", category=RuntimeWarning)
+warnings.filterwarnings("ignore", category=FutureWarning)
+
 from nazoru.led import LED_BLUE, LED_RED, LED_CHASSIS
 import time
 LED_RED.blink(1)
@@ -67,7 +73,16 @@ def main():
 
     LED_CHASSIS.set_brightness(100)
     LED_RED.on()
-    result = predictor.predict_top_n(data, 5)
+    try:
+      result = predictor.predict_top_n(data, 5)
+    except IndexError:
+      # This is possible when pressing keys we don't use for learning.
+      print('Invalid input. (out of range)')
+      continue
+    except ValueError:
+      # This is possible when pressing only one key.
+      print('Invalid input. (one key)')
+      continue
     LED_RED.off()
     LED_CHASSIS.set_brightness(5)