diff --git a/share/chruby/chruby.sh b/share/chruby/chruby.sh
index 2943fe43..53774163 100644
--- a/share/chruby/chruby.sh
+++ b/share/chruby/chruby.sh
@@ -1,6 +1,6 @@
 typeset -a RUBIES
 
-function chruby_reset()
+function __chruby_reset()
 {
 	[[ -z "$RUBY" ]] && return
 
@@ -19,10 +19,10 @@ function chruby_reset()
 	hash -r
 }
 
-function chruby_use()
+function __chruby_use()
 {
 	[[ "$RUBY" == "$1" && "$RUBYOPT" == "$2" ]] && return
-	[[ -n "$RUBY" ]] && chruby_reset
+	[[ -n "$RUBY" ]] && __chruby_reset
 
 	export RUBY="$1"
 	export RUBYOPT="$2"
@@ -42,6 +42,17 @@ EOF`
 	fi
 }
 
+__complete_chruby() {
+  local cur rubie basenames
+  typeset -a basenames
+  cur="${COMP_WORDS[COMP_CWORD]}"
+  for rubie in ${RUBIES[@]}; do
+    basenames+=($(basename $rubie))
+  done
+  COMPREPLY=( $(compgen -W "${basenames[*]}" -- ${cur}) )
+}
+complete -F __complete_chruby chruby
+
 function chruby()
 {
 	local ruby_path
@@ -61,12 +72,12 @@ function chruby()
 				echo " $star $(basename "$ruby_path")"
 			done
 			;;
-		system) chruby_reset ;;
+		system) __chruby_reset ;;
 		*)
 			for ruby_path in ${RUBIES[@]}; do
 				if [[ `basename "$ruby_path"` == *$1* ]]; then
 					shift
-					chruby_use "$ruby_path" "$*"
+					__chruby_use "$ruby_path" "$*"
 					return
 				fi
 			done
diff --git a/test/chruby_reset_test.sh b/test/chruby_reset_test.sh
index d147b927..e24e30de 100755
--- a/test/chruby_reset_test.sh
+++ b/test/chruby_reset_test.sh
@@ -12,12 +12,12 @@ setUp()
 
 	export PATH="$GEM_HOME/bin:$GEM_ROOT/bin:$RUBY/bin:$TEST_PATH"
 
-	chruby_use "$TEST_RUBY"
+	__chruby_use "$TEST_RUBY"
 }
 
-test_chruby_reset()
+test___chruby_reset()
 {
-	chruby_reset
+	__chruby_reset
 
 	assertNull "RUBY was not unset"          "$RUBY"
 	assertNull "RUBY_ENGINE was not unset"   "$RUBY_ENGINE"
@@ -29,11 +29,11 @@ test_chruby_reset()
 	assertEquals "PATH was not sanitized"    "$TEST_PATH" "$PATH"
 }
 
-test_chruby_reset_duplicate_path()
+test___chruby_reset_duplicate_path()
 {
 	export PATH="$PATH:$GEM_HOME/bin:$GEM_ROOT/bin:$RUBY/bin"
 
-	chruby_reset
+	__chruby_reset
 
 	assertEquals "PATH was not sanitized"    "$TEST_PATH" "$PATH"
 }
diff --git a/test/chruby_test.sh b/test/chruby_test.sh
index 804fdf4c..4e741b62 100755
--- a/test/chruby_test.sh
+++ b/test/chruby_test.sh
@@ -4,17 +4,17 @@
 
 tearDown()
 {
-	chruby_reset
+	__chruby_reset
 }
 
-test_chruby_1_9()
+test___chruby_1_9()
 {
 	chruby "1.9"
 
 	assertEquals "did not match $TEST_RUBY with 1.9" "$TEST_RUBY" "$RUBY"
 }
 
-test_chruby_system()
+test___chruby_system()
 {
 	chruby "$TEST_RUBY_VERSION"
 	chruby system
@@ -22,7 +22,7 @@ test_chruby_system()
 	assertNull "did not reset the Ruby" "$RUBY"
 }
 
-test_chruby_unknown()
+test___chruby_unknown()
 {
 	chruby "foo" 2>/dev/null
 
diff --git a/test/chruby_use_test.sh b/test/chruby_use_test.sh
index 6c3ffe14..33b5322a 100755
--- a/test/chruby_use_test.sh
+++ b/test/chruby_use_test.sh
@@ -4,10 +4,10 @@
 
 setUp()
 {
-	chruby_use $TEST_RUBY
+	__chruby_use $TEST_RUBY
 }
 
-test_chruby_use()
+test___chruby_use()
 {
 	assertEquals "invalid RUBY" "$TEST_RUBY" "$RUBY"
 	assertEquals "invalid RUBY_ENGINE"  "$TEST_RUBY_ENGINE" "$RUBY_ENGINE"
@@ -20,7 +20,7 @@ test_chruby_use()
 }
 
 tearDown() {
-	chruby_reset
+	__chruby_reset
 }
 
 SHUNIT_PARENT=$0 . /usr/share/shunit2/shunit2
diff --git a/test/helper.sh b/test/helper.sh
index 3f7d8534..cf146c76 100644
--- a/test/helper.sh
+++ b/test/helper.sh
@@ -4,7 +4,7 @@
 
 . ./share/chruby/chruby.sh
 
-chruby_reset
+__chruby_reset
 
 TEST_PATH="$PATH"
 TEST_RUBY_ENGINE="ruby"