diff --git a/libexec/pyenv-local b/libexec/pyenv-local
index 8bb40fab..529cbf01 100755
--- a/libexec/pyenv-local
+++ b/libexec/pyenv-local
@@ -38,13 +38,14 @@ versions=($@)
 if [ "$versions" = "--unset" ]; then
   rm -f .python-version .pyenv-version
 elif [ -n "$versions" ]; then
-  if [ "$(PYENV_VERSION= pyenv-version-origin)" -ef .pyenv-version ]; then
+  previous_file="$(PYENV_VERSION= pyenv-version-origin || true)"
+  pyenv-version-file-write .python-version "${versions[@]}"
+  if [ "$previous_file" -ef .pyenv-version ]; then
     rm -f .pyenv-version
     { echo "pyenv: removed existing \`.pyenv-version' file and migrated"
       echo "       local version specification to \`.python-version' file"
     } >&2
   fi
-  pyenv-version-file-write .python-version "${versions[@]}"
 else
   OLDIFS="$IFS"
   IFS=: versions=($(
diff --git a/libexec/pyenv-prefix b/libexec/pyenv-prefix
index 64f6f391..a25ff030 100755
--- a/libexec/pyenv-prefix
+++ b/libexec/pyenv-prefix
@@ -16,32 +16,38 @@ if [ "$1" = "--complete" ]; then
 fi
 
 if [ -n "$1" ]; then
-  versions=($@)
   OLDIFS="$IFS"
-  IFS=: PYENV_VERSION="${versions[*]}"
-  IFS="$OLDIFS"
-  export PYENV_VERSION
-else
-  OLDIFS="$IFS"
-  IFS=: versions=($(pyenv-version-name))
+  { IFS=:
+    export PYENV_VERSION="$*"
+  }
   IFS="$OLDIFS"
+elif [ -z "$PYENV_VERSION" ]; then
+  PYENV_VERSION="$(pyenv-version-name)"
 fi
 
 PYENV_PREFIX_PATHS=()
-for version in "${versions[@]}"; do
-  if [ "$version" = "system" ]; then
-    PYTHON_PATH="$(PYENV_VERSION="${version}" pyenv-which python || true)"
-    PYENV_PREFIX_PATH="${PYTHON_PATH%/bin/*}"
-  else
-    PYENV_PREFIX_PATH="${PYENV_ROOT}/versions/${version}"
-  fi
-  if [ -d "$PYENV_PREFIX_PATH" ]; then
-    PYENV_PREFIX_PATHS=("${PYENV_PREFIX_PATHS[@]}" "$PYENV_PREFIX_PATH")
-  else
-    echo "pyenv: version \`${version}' not installed" >&2
-    exit 1
-  fi
-done
+OLDIFS="$IFS"
+{ IFS=:
+  for version in ${PYENV_VERSION}; do
+    if [ "$version" = "system" ]; then
+      if PYTHON_PATH="$(pyenv-which python 2>/dev/null)"; then
+        PYENV_PREFIX_PATH="${PYTHON_PATH%/bin/*}"
+      else
+        echo "pyenv: system version not found in PATH" >&2
+        exit 1
+      fi
+    else
+      PYENV_PREFIX_PATH="${PYENV_ROOT}/versions/${version}"
+    fi
+    if [ -d "$PYENV_PREFIX_PATH" ]; then
+      PYENV_PREFIX_PATHS=("${PYENV_PREFIX_PATHS[@]}" "$PYENV_PREFIX_PATH")
+    else
+      echo "pyenv: version \`${version}' not installed" >&2
+      exit 1
+    fi
+  done
+}
+IFS="$OLDIFS"
 
 OLDIFS="$IFS"
 { IFS=:
diff --git a/libexec/pyenv-version-file-write b/libexec/pyenv-version-file-write
index 6441909e..5ec01b6c 100755
--- a/libexec/pyenv-version-file-write
+++ b/libexec/pyenv-version-file-write
@@ -5,7 +5,7 @@ set -e
 [ -n "$PYENV_DEBUG" ] && set -x
 
 PYENV_VERSION_FILE="$1"
-shift
+shift || true
 versions=("$@")
 
 if [ -z "$versions" ] || [ -z "$PYENV_VERSION_FILE" ]; then
diff --git a/libexec/pyenv-version-name b/libexec/pyenv-version-name
index 368ccb97..c15178e2 100755
--- a/libexec/pyenv-version-name
+++ b/libexec/pyenv-version-name
@@ -5,18 +5,10 @@ set -e
 
 if [ -z "$PYENV_VERSION" ]; then
   PYENV_VERSION_FILE="$(pyenv-version-file)"
-  OLDIFS="$IFS"
-  IFS=: versions=($(pyenv-version-file-read "$PYENV_VERSION_FILE" || true))
-  IFS=: PYENV_VERSION="${versions[*]}"
-  IFS="$OLDIFS"
-  export PYENV_VERSION
-else
-  OLDIFS="$IFS"
-  IFS=: versions=($(echo "${PYENV_VERSION}"))
-  IFS="$OLDIFS"
+  PYENV_VERSION="$(pyenv-version-file-read "$PYENV_VERSION_FILE" || true)"
 fi
 
-if [ -z "$versions" ] || [ "$versions" = "system" ]; then
+if [ -z "$PYENV_VERSION" ] || [ "$PYENV_VERSION" = "system" ]; then
   echo "system"
   exit
 fi
@@ -26,11 +18,27 @@ version_exists() {
   [ -d "${PYENV_ROOT}/versions/${version}" ]
 }
 
-for version in "${versions[@]}"; do
-  if [ "$version" != "system" ] && ! version_exists "$version"; then
-    echo "pyenv: version \`$version' is not installed" >&2
-    exit 1
-  fi
-done
+versions=()
+OLDIFS="$IFS"
+{ IFS=:
+  for version in ${PYENV_VERSION}; do
+    if version_exists "$version" || [ "$version" = "system" ]; then
+      versions=("${versions[@]}" "${version}")
+    elif version_exists "${version#python-}"; then
+      { echo "warning: ignoring extraneous \`python-' prefix in version \`${version}'"
+        echo "         (set by $(pyenv-version-origin))"
+      } >&2
+      versions=("${versions[@]}" "${version#python-}")
+    else
+      echo "pyenv: version \`$version' is not installed" >&2
+      exit 1
+    fi
+  done
+}
+IFS="$OLDIFS"
 
-echo "${PYENV_VERSION}"
+OLDIFS="$IFS"
+{ IFS=:
+  echo "${versions[*]}"
+}
+IFS="$OLDIFS"
diff --git a/test/exec.bats b/test/exec.bats
index c81db709..817d1aee 100644
--- a/test/exec.bats
+++ b/test/exec.bats
@@ -29,8 +29,8 @@ create_executable() {
   run pyenv-completions exec
   assert_success
   assert_output <<OUT
-rake
 python
+rake
 OUT
 }
 
diff --git a/test/libexec/rbenv-echo b/test/libexec/pyenv-echo
similarity index 100%
rename from test/libexec/rbenv-echo
rename to test/libexec/pyenv-echo
diff --git a/test/rbenv.bats b/test/pyenv.bats
similarity index 94%
rename from test/rbenv.bats
rename to test/pyenv.bats
index e16b636d..bcc9b2b8 100644
--- a/test/rbenv.bats
+++ b/test/pyenv.bats
@@ -5,7 +5,7 @@ load test_helper
 @test "blank invocation" {
   run pyenv
   assert_success
-  assert [ "${lines[0]}" = "pyenv 0.4.0" ]
+  assert [ "${lines[0]}" == "pyenv 0.4.0-20131217" ]
 }
 
 @test "invalid command" {
diff --git a/test/rehash.bats b/test/rehash.bats
index fbe70f83..b6682a98 100755
--- a/test/rehash.bats
+++ b/test/rehash.bats
@@ -47,9 +47,9 @@ create_executable() {
   run ls "${PYENV_ROOT}/shims"
   assert_success
   assert_output <<OUT
+python
 rake
 rspec
-python
 OUT
 }
 
@@ -80,8 +80,8 @@ OUT
   run ls "${PYENV_ROOT}/shims"
   assert_success
   assert_output <<OUT
-rspec
 python
+rspec
 OUT
 }
 
diff --git a/test/version-file-read.bats b/test/version-file-read.bats
index c9d19e51..7414aa01 100644
--- a/test/version-file-read.bats
+++ b/test/version-file-read.bats
@@ -38,7 +38,7 @@ setup() {
 @test "reads only the first word from file" {
   cat > my-version <<<"1.9.3-p194@tag 1.8.7 hi"
   run pyenv-version-file-read my-version
-  assert_success "1.9.3-p194@tag"
+  assert_success "1.9.3-p194@tag:1.8.7:hi"
 }
 
 @test "loads only the first line in file" {
@@ -47,7 +47,7 @@ setup() {
 1.9.3 two
 IN
   run pyenv-version-file-read my-version
-  assert_success "1.8.7"
+  assert_success "1.8.7:one:1.9.3:two"
 }
 
 @test "ignores leading blank lines" {