diff --git a/bin/pyenv-sh-activate b/bin/pyenv-sh-activate
index 547c6bb..eaa6b75 100755
--- a/bin/pyenv-sh-activate
+++ b/bin/pyenv-sh-activate
@@ -75,6 +75,16 @@ if [ -z "$no_shell" ]; then
 fi
 
 case "$shell" in
-fish ) echo ". \"$(pyenv-prefix "${versions}")/bin/activate.fish\"" ;;
-*    ) echo "source \"$(pyenv-prefix "${versions}")/bin/activate\"" ;;
+fish )
+  cat <<EOS
+set -e PYENV_DEACTIVATE;
+. "$(pyenv-prefix "${versions}")/bin/activate.fish";
+EOS
+ ;;
+*    )
+  cat <<EOS
+unset PYENV_DEACTIVATE;
+source "$(pyenv-prefix "${versions}")/bin/activate";
+EOS
+  ;;
 esac
diff --git a/bin/pyenv-sh-deactivate b/bin/pyenv-sh-deactivate
index 38b08fb..85e2803 100755
--- a/bin/pyenv-sh-deactivate
+++ b/bin/pyenv-sh-deactivate
@@ -11,12 +11,26 @@ set -e
 
 shell="$(basename "${PYENV_SHELL:-$SHELL}")"
 case "$shell" in
-fish ) echo "functions -q deactivate; and deactivate;";;
-*    ) echo "declare -f deactivate 1>/dev/null 2>&1 && deactivate;";;
+fish )
+  cat <<EOS
+if functions -q deactivate
+  setenv PYENV_DEACTIVATE "\$VIRTUAL_ENV";
+  deactivate;
+end;
+EOS
+  ;;
+*    )
+  cat <<EOS
+if declare -f deactivate 1>/dev/null 2>&1; then
+  export PYENV_DEACTIVATE="\$VIRTUAL_ENV";
+  deactivate;
+fi;
+EOS
+  ;;
 esac
 
 if [ -z "${PYENV_VIRTUALENV_INIT}" ]; then
   # Backward compatibility issue
   # https://github.com/yyuu/pyenv-virtualenv/issues/26
-  echo "pyenv shell --unset"
+  echo "pyenv shell --unset;"
 fi
diff --git a/bin/pyenv-virtualenv-init b/bin/pyenv-virtualenv-init
index cdf6f8d..8e0b11c 100755
--- a/bin/pyenv-virtualenv-init
+++ b/bin/pyenv-virtualenv-init
@@ -63,53 +63,84 @@ if [ -z "$print" ]; then
 fi
 
 case "$shell" in
-bash )
+fish )
+  echo "setenv PYENV_VIRTUALENV_INIT 1;"
+  ;;
+* )
+  echo "export PYENV_VIRTUALENV_INIT=1;"
+  ;;
+esac
+
+case "$shell" in
+fish )
+  cat <<EOS
+function _pyenv_virtualenv_hook --on-event fish_prompt;
+  if [ -n "\$VIRTUAL_ENV" ]
+    if [ (pyenv version-name) = "system" ]
+      eval (pyenv sh-deactivate); or true
+      return 0
+    end
+    if [ "\$VIRTUAL_ENV" != (pyenv prefix) ]
+      eval (pyenv sh-deactivate); or true
+      eval (pyenv sh-activate 2>/dev/null); or true
+    end
+  else
+    if [ "\$PYENV_DEACTIVATE" != (pyenv prefix) ]
+      eval (pyenv sh-activate 2>/dev/null); or true
+    end
+  end
+end
+EOS
+ ;;
+ksh )
+  cat <<EOS
+function _pyenv_virtualenv_hook() {
+EOS
+  ;;
+* )
   cat <<EOS
-export PYENV_VIRTUALENV_INIT=1
 _pyenv_virtualenv_hook() {
-  if [[ "\$(pyenv version-name)" == "system" ]]; then
-    pyenv deactivate || true;
-  elif [[ "\$VIRTUAL_ENV" != "\$(pyenv prefix)" ]]; then
-    pyenv deactivate || true;
-    pyenv activate 2>/dev/null || true
+EOS
+  ;;
+esac
+
+if [[ "$shell" != "fish" ]]; then
+  cat <<EOS
+  if [ -n "\$VIRTUAL_ENV" ]; then
+    if [ "x\`pyenv version-name\`" = "xsystem" ]; then
+      pyenv deactivate || true
+      return 0
+    fi
+    if [ "x\$VIRTUAL_ENV" != "x\`pyenv prefix\`" ]; then
+      pyenv deactivate || true
+      pyenv activate 2>/dev/null || true
+    fi
+  else
+    if [ "x\$PYENV_DEACTIVATE" != "x\`pyenv prefix\`" ]; then
+      pyenv activate 2>/dev/null || true
+    fi
   fi
 };
+EOS
+
+  case "$shell" in
+  bash )
+    cat <<EOS
 if ! [[ "\$PROMPT_COMMAND" =~ _pyenv_virtualenv_hook ]]; then
   PROMPT_COMMAND="_pyenv_virtualenv_hook;\$PROMPT_COMMAND";
 fi
 EOS
-  ;;
-fish )
-  cat <<EOS
-setenv PYENV_VIRTUALENV_INIT 1;
-function _pyenv_virtualenv_hook --on-event fish_prompt;
-  if [ (pyenv version-name) = "system" ]
-    eval (pyenv sh-deactivate); or true
-  else if [ "\$VIRTUAL_ENV" != (pyenv prefix) ]
-    eval (pyenv sh-deactivate); or true
-    eval (pyenv sh-activate 2>/dev/null); or true
-  end
-end
-EOS
-  ;;
-zsh )
-  cat <<EOS
-export PYENV_VIRTUALENV_INIT=1
-_pyenv_virtualenv_hook() {
-  if [[ "\$(pyenv version-name)" == "system" ]]; then
-    pyenv deactivate || true
-  elif [[ "\$VIRTUAL_ENV" != "\$(pyenv prefix)" ]]; then
-    pyenv deactivate || true
-    pyenv activate 2>/dev/null || true
-  fi
-}
+    ;;
+  zsh )
+    cat <<EOS
 typeset -a precmd_functions
 if [[ -z \$precmd_functions[(r)_pyenv_virtualenv_hook] ]]; then
   precmd_functions+=_pyenv_virtualenv_hook;
 fi
 EOS
-  ;;
-* )
-  # FIXME: what should i do here??
-  ;;
-esac
+    ;;
+  * )
+    # FIXME: what should i do here??
+    ;;
+  esac
+fi
diff --git a/test/activate.bats b/test/activate.bats
index f1e98ea..a6a65d0 100644
--- a/test/activate.bats
+++ b/test/activate.bats
@@ -22,7 +22,8 @@ setup() {
 
   assert_success
   assert_output <<EOS
-source "${PYENV_ROOT}/versions/venv/bin/activate"
+unset PYENV_DEACTIVATE;
+source "${PYENV_ROOT}/versions/venv/bin/activate";
 EOS
 }
 
@@ -42,7 +43,8 @@ EOS
   assert_success
   assert_output <<EOS
 pyenv shell "venv";
-source "${PYENV_ROOT}/versions/venv/bin/activate"
+unset PYENV_DEACTIVATE;
+source "${PYENV_ROOT}/versions/venv/bin/activate";
 EOS
 }
 
@@ -61,7 +63,8 @@ EOS
 
   assert_success
   assert_output <<EOS
-. "${PYENV_ROOT}/versions/venv/bin/activate.fish"
+set -e PYENV_DEACTIVATE;
+. "${PYENV_ROOT}/versions/venv/bin/activate.fish";
 EOS
 }
 
@@ -81,7 +84,8 @@ EOS
   assert_success
   assert_output <<EOS
 pyenv shell "venv";
-. "${PYENV_ROOT}/versions/venv/bin/activate.fish"
+set -e PYENV_DEACTIVATE;
+. "${PYENV_ROOT}/versions/venv/bin/activate.fish";
 EOS
 }
 
@@ -99,7 +103,8 @@ EOS
   assert_success
   assert_output <<EOS
 pyenv shell "venv27";
-source "${PYENV_ROOT}/versions/venv27/bin/activate"
+unset PYENV_DEACTIVATE;
+source "${PYENV_ROOT}/versions/venv27/bin/activate";
 EOS
 }
 
@@ -117,7 +122,8 @@ EOS
   assert_success
   assert_output <<EOS
 pyenv shell "venv27";
-source "${PYENV_ROOT}/versions/venv27/bin/activate"
+unset PYENV_DEACTIVATE;
+source "${PYENV_ROOT}/versions/venv27/bin/activate";
 EOS
 }
 
diff --git a/test/deactivate.bats b/test/deactivate.bats
index 79427ea..1f8331a 100644
--- a/test/deactivate.bats
+++ b/test/deactivate.bats
@@ -13,7 +13,10 @@ setup() {
 
   assert_success
   assert_output <<EOS
-declare -f deactivate 1>/dev/null 2>&1 && deactivate;
+if declare -f deactivate 1>/dev/null 2>&1; then
+  export PYENV_DEACTIVATE="\$VIRTUAL_ENV";
+  deactivate;
+fi;
 EOS
 }
 
@@ -24,8 +27,11 @@ EOS
 
   assert_success
   assert_output <<EOS
-declare -f deactivate 1>/dev/null 2>&1 && deactivate;
-pyenv shell --unset
+if declare -f deactivate 1>/dev/null 2>&1; then
+  export PYENV_DEACTIVATE="\$VIRTUAL_ENV";
+  deactivate;
+fi;
+pyenv shell --unset;
 EOS
 }
 
@@ -36,7 +42,10 @@ EOS
 
   assert_success
   assert_output <<EOS
-functions -q deactivate; and deactivate;
+if functions -q deactivate
+  setenv PYENV_DEACTIVATE "\$VIRTUAL_ENV";
+  deactivate;
+end;
 EOS
 }
 
@@ -47,8 +56,11 @@ EOS
 
   assert_success
   assert_output <<EOS
-functions -q deactivate; and deactivate;
-pyenv shell --unset
+if functions -q deactivate
+  setenv PYENV_DEACTIVATE "\$VIRTUAL_ENV";
+  deactivate;
+end;
+pyenv shell --unset;
 EOS
 }
 
diff --git a/test/init.bats b/test/init.bats
index 5071396..afd03ce 100644
--- a/test/init.bats
+++ b/test/init.bats
@@ -29,13 +29,21 @@ load test_helper
   run pyenv-virtualenv-init - bash
   assert_success
   assert_output <<EOS
-export PYENV_VIRTUALENV_INIT=1
+export PYENV_VIRTUALENV_INIT=1;
 _pyenv_virtualenv_hook() {
-  if [[ "\$(pyenv version-name)" == "system" ]]; then
-    pyenv deactivate || true;
-  elif [[ "\$VIRTUAL_ENV" != "\$(pyenv prefix)" ]]; then
-    pyenv deactivate || true;
-    pyenv activate 2>/dev/null || true
+  if [ -n "\$VIRTUAL_ENV" ]; then
+    if [ "x\`pyenv version-name\`" = "xsystem" ]; then
+      pyenv deactivate || true
+      return 0
+    fi
+    if [ "x\$VIRTUAL_ENV" != "x\`pyenv prefix\`" ]; then
+      pyenv deactivate || true
+      pyenv activate 2>/dev/null || true
+    fi
+  else
+    if [ "x\$PYENV_DEACTIVATE" != "x\`pyenv prefix\`" ]; then
+      pyenv activate 2>/dev/null || true
+    fi
   fi
 };
 if ! [[ "\$PROMPT_COMMAND" =~ _pyenv_virtualenv_hook ]]; then
@@ -50,11 +58,19 @@ EOS
   assert_output <<EOS
 setenv PYENV_VIRTUALENV_INIT 1;
 function _pyenv_virtualenv_hook --on-event fish_prompt;
-  if [ (pyenv version-name) = "system" ]
-    eval (pyenv sh-deactivate); or true
-  else if [ "\$VIRTUAL_ENV" != (pyenv prefix) ]
-    eval (pyenv sh-deactivate); or true
-    eval (pyenv sh-activate 2>/dev/null); or true
+  if [ -n "\$VIRTUAL_ENV" ]
+    if [ (pyenv version-name) = "system" ]
+      eval (pyenv sh-deactivate); or true
+      return 0
+    end
+    if [ "\$VIRTUAL_ENV" != (pyenv prefix) ]
+      eval (pyenv sh-deactivate); or true
+      eval (pyenv sh-activate 2>/dev/null); or true
+    end
+  else
+    if [ "\$PYENV_DEACTIVATE" != (pyenv prefix) ]
+      eval (pyenv sh-activate 2>/dev/null); or true
+    end
   end
 end
 EOS
@@ -64,15 +80,23 @@ EOS
   run pyenv-virtualenv-init - zsh
   assert_success
   assert_output <<EOS
-export PYENV_VIRTUALENV_INIT=1
+export PYENV_VIRTUALENV_INIT=1;
 _pyenv_virtualenv_hook() {
-  if [[ "\$(pyenv version-name)" == "system" ]]; then
-    pyenv deactivate || true
-  elif [[ "\$VIRTUAL_ENV" != "\$(pyenv prefix)" ]]; then
-    pyenv deactivate || true
-    pyenv activate 2>/dev/null || true
+  if [ -n "\$VIRTUAL_ENV" ]; then
+    if [ "x\`pyenv version-name\`" = "xsystem" ]; then
+      pyenv deactivate || true
+      return 0
+    fi
+    if [ "x\$VIRTUAL_ENV" != "x\`pyenv prefix\`" ]; then
+      pyenv deactivate || true
+      pyenv activate 2>/dev/null || true
+    fi
+  else
+    if [ "x\$PYENV_DEACTIVATE" != "x\`pyenv prefix\`" ]; then
+      pyenv activate 2>/dev/null || true
+    fi
   fi
-}
+};
 typeset -a precmd_functions
 if [[ -z \$precmd_functions[(r)_pyenv_virtualenv_hook] ]]; then
   precmd_functions+=_pyenv_virtualenv_hook;