diff --git a/lib/irb/completion.rb b/lib/irb/completion.rb
index e35fe2a5a3..58328c2490 100644
--- a/lib/irb/completion.rb
+++ b/lib/irb/completion.rb
@@ -192,7 +192,7 @@ module IRB
         sym = $1
         candidates = Symbol.all_symbols.collect do |s|
           ":" + s.id2name.encode(Encoding.default_external)
-        rescue Encoding::UndefinedConversionError
+        rescue EncodingError
           # ignore
         rescue Encoding::InvalidByteSequenceError => e
           raise "Invalid byte sequence #{s.id2name.bytes.inspect} #{e.inspect}"
diff --git a/test/irb/test_completion.rb b/test/irb/test_completion.rb
index d94c471996..a1aa4b898d 100644
--- a/test/irb/test_completion.rb
+++ b/test/irb/test_completion.rb
@@ -27,6 +27,10 @@ module TestIRB
     end
 
     def test_complete_symbol
+      %w"UTF-16LE UTF-7".each do |enc|
+        "K".force_encoding(enc).to_sym
+      rescue
+      end
       _ = :aiueo
       assert_include(IRB::InputCompletor.retrieve_completion_data(":a", bind: binding), ":aiueo")
       assert_empty(IRB::InputCompletor.retrieve_completion_data(":irb_unknown_symbol_abcdefg", bind: binding))