diff --git a/fzf b/fzf
index 2f90861..8cd2756 100755
--- a/fzf
+++ b/fzf
@@ -366,7 +366,8 @@ class FZF
     end if str
   end
   def addstr_safe str
-    C.addstr str.gsub("\0", '')
+    str = str.gsub("\0", '') rescue str
+    C.addstr str
   end
 
   def print_input
@@ -1105,7 +1106,7 @@ class FZF
         begin
           unless @delim
             # AWK default
-            prefix_length = (str.index(/\S/) rescue 0)|| 0
+            prefix_length = (str.index(/\S/) || 0) rescue 0
             tokens = str.scan(/\S+\s*/) rescue []
           else
             prefix_length = 0
diff --git a/test/test_fzf.rb b/test/test_fzf.rb
index 4f9e6e1..806df8a 100644
--- a/test/test_fzf.rb
+++ b/test/test_fzf.rb
@@ -5,6 +5,7 @@ require 'curses'
 require 'timeout'
 require 'stringio'
 require 'minitest/autorun'
+require 'tempfile'
 $LOAD_PATH.unshift File.expand_path('../..', __FILE__)
 ENV['FZF_EXECUTABLE'] = '0'
 load 'fzf'
@@ -614,7 +615,7 @@ class TestFZF < MiniTest::Unit::TestCase
   def test_select_1_ambiguity
     stream = stream_for "Hello\nWorld"
     begin
-      Timeout::timeout(3) do
+      Timeout::timeout(2) do
         FZF.new(%w[--query=o --select-1], stream).start
       end
       flunk 'Should not reach here'
@@ -681,5 +682,19 @@ class TestFZF < MiniTest::Unit::TestCase
     # **[*****  #] => [******# ]
     assert_equal [true, 0, 6], fzf.constrain(2, 10, 7, 10)
   end
+
+  def test_invalid_utf8
+    tmp = Tempfile.new('fzf')
+    tmp << 'hello ' << [0xff].pack('C*') << ' world' << $/ << [0xff].pack('C*')
+    tmp.close
+    begin
+      Timeout::timeout(1) do
+        FZF.new(%w[-n..,1,2.. -q^ -x], File.open(tmp.path)).start
+      end
+    rescue Timeout::Error
+    end
+  ensure
+    tmp.unlink
+  end
 end