diff --git a/nvm.sh b/nvm.sh
index 11ded0d..f75d9b0 100644
--- a/nvm.sh
+++ b/nvm.sh
@@ -200,10 +200,11 @@ nvm_version() {
   fi
 
   VERSION="$(nvm_ls "$PATTERN" | tail -n1)"
-  echo "$VERSION"
-
-  if [ "$VERSION" = 'N/A' ]; then
-    return 3
+  if [ -z "$VERSION" ] || [ "_$VERSION" = "_N/A" ]; then
+    echo "N/A"
+    return 3;
+  else
+    echo "$VERSION"
   fi
 }
 
@@ -278,7 +279,7 @@ nvm_binary_available() {
   # binaries started with node 0.8.6
   local FIRST_VERSION_WITH_BINARY
   FIRST_VERSION_WITH_BINARY="0.8.6"
-  nvm_version_greater_than_or_equal_to "$1" "$FIRST_VERSION_WITH_BINARY"
+  nvm_version_greater_than_or_equal_to "$(nvm_strip_iojs_prefix $1)" "$FIRST_VERSION_WITH_BINARY"
 }
 
 nvm_alias() {
@@ -411,20 +412,31 @@ nvm_ls() {
     return
   fi
 
+  case "$PATTERN" in
+    "$(nvm_iojs_prefix)" | "$(nvm_node_prefix)")
+      PATTERN="$PATTERN-"
+    ;;
+    *)
+      PATTERN=$(nvm_ensure_version_prefix $PATTERN)
+    ;;
+  esac
   # If it looks like an explicit version, don't do anything funny
-  PATTERN=$(nvm_ensure_version_prefix $PATTERN)
   if [ "_$(echo "$PATTERN" | cut -c1-1)" = "_v" ] && [ "_$(nvm_num_version_groups "$PATTERN")" = "_3" ]; then
     if [ -d "$(nvm_version_path "$PATTERN")" ]; then
       VERSIONS="$PATTERN"
     fi
   else
-    if [ "_$PATTERN" != "_system" ]; then
-      local NUM_VERSION_GROUPS
-      NUM_VERSION_GROUPS="$(nvm_num_version_groups "$PATTERN")"
-      if [ "_$NUM_VERSION_GROUPS" = "_2" ] || [ "_$NUM_VERSION_GROUPS" = "_1" ]; then
-        PATTERN="$(echo "$PATTERN" | command sed -e 's/\.*$//g')."
-      fi
-    fi
+    case "$PATTERN" in
+      "$(nvm_iojs_prefix)-" | "$(nvm_node_prefix)-" | "system")
+      ;;
+      *)
+        local NUM_VERSION_GROUPS
+        NUM_VERSION_GROUPS="$(nvm_num_version_groups "$PATTERN")"
+        if [ "_$NUM_VERSION_GROUPS" = "_2" ] || [ "_$NUM_VERSION_GROUPS" = "_1" ]; then
+          PATTERN="$(echo "$PATTERN" | command sed -e 's/\.*$//g')."
+        fi
+      ;;
+    esac
 
     local ZHS_HAS_SHWORDSPLIT_UNSET
     ZHS_HAS_SHWORDSPLIT_UNSET=1
@@ -435,11 +447,25 @@ nvm_ls() {
 
     local NVM_DIRS_TO_TEST_AND_SEARCH
     local NVM_DIRS_TO_SEARCH
+    local NVM_ADD_SYSTEM
+    NVM_ADD_SYSTEM=false
     if nvm_is_iojs_version "$PATTERN"; then
       NVM_DIRS_TO_TEST_AND_SEARCH="$(nvm_version_dir iojs)"
       PATTERN="$(nvm_strip_iojs_prefix "$PATTERN")"
+      if nvm_has_system_iojs; then
+        NVM_ADD_SYSTEM=true
+      fi
+    elif [ "_$PATTERN" = "_$(nvm_node_prefix)-" ]; then
+      NVM_DIRS_TO_TEST_AND_SEARCH="$(nvm_version_dir old) $(nvm_version_dir new)"
+      PATTERN=''
+      if nvm_has_system_node; then
+        NVM_ADD_SYSTEM=true
+      fi
     else
       NVM_DIRS_TO_TEST_AND_SEARCH="$(nvm_version_dir old) $(nvm_version_dir new) $(nvm_version_dir iojs)"
+      if nvm_has_system_iojs || nvm_has_system_node; then
+        NVM_ADD_SYSTEM=true
+      fi
     fi
     for NVM_VERSION_DIR in $NVM_DIRS_TO_TEST_AND_SEARCH; do
       if [ -d "$NVM_VERSION_DIR" ]; then
@@ -467,7 +493,7 @@ nvm_ls() {
     fi
   fi
 
-  if nvm_has_system_node || nvm_has_system_iojs; then
+  if [ "$NVM_ADD_SYSTEM" = true ]; then
     if [ -z "$PATTERN" ] || [ "_$PATTERN" = "_v" ]; then
       VERSIONS="$VERSIONS$(command printf '\n%s' 'system')"
     elif [ "$PATTERN" = 'system' ]; then
@@ -1080,16 +1106,31 @@ nvm() {
         nvm help
         return 127
       fi
+
       if [ $# -eq 1 ]; then
         nvm_rc_version
         if [ -n "$NVM_RC_VERSION" ]; then
           VERSION="$(nvm_version "$NVM_RC_VERSION")"
         fi
-      elif [ "_$2" != '_system' ]; then
-        VERSION="$(nvm_version "$2")"
       else
-        VERSION="$2"
+        local NVM_IOJS_PREFIX
+        NVM_IOJS_PREFIX="$(nvm_iojs_prefix)"
+        case "_$2" in
+          "_$NVM_IOJS_PREFIX" | "_io.js")
+            VERSION="$(nvm_add_iojs_prefix $(nvm_ls | command grep "$NVM_IOJS_PREFIX" | tail -n1))"
+          ;;
+          "_$(nvm_node_prefix)")
+            VERSION="$(nvm_version stable)"
+          ;;
+          "_system")
+            VERSION="system"
+          ;;
+          *)
+            VERSION="$(nvm_version "$2")"
+          ;;
+        esac
       fi
+
       if [ -z "$VERSION" ]; then
         nvm help
         return 127
diff --git "a/test/fast/Listing versions/Running \"nvm ls node\" should return a nonzero exit code when not found" "b/test/fast/Listing versions/Running \"nvm ls node_\" should return a nonzero exit code when not found"
similarity index 78%
rename from "test/fast/Listing versions/Running \"nvm ls node\" should return a nonzero exit code when not found"
rename to "test/fast/Listing versions/Running \"nvm ls node_\" should return a nonzero exit code when not found"
index f7d68f7..2d6b012 100755
--- "a/test/fast/Listing versions/Running \"nvm ls node\" should return a nonzero exit code when not found"	
+++ "b/test/fast/Listing versions/Running \"nvm ls node_\" should return a nonzero exit code when not found"	
@@ -2,6 +2,6 @@
 
 . ../../../nvm.sh
 
-nvm ls node
+nvm ls node_
 [ "$?" = "3" ]
 
diff --git a/test/fast/Unit tests/nvm_version b/test/fast/Unit tests/nvm_version
new file mode 100755
index 0000000..7babb8c
--- /dev/null
+++ b/test/fast/Unit tests/nvm_version	
@@ -0,0 +1,47 @@
+#!/bin/sh
+
+die () { echo $@ ; cleanup ; exit 1; }
+cleanup () {
+  unset -f nvm_ls_current nvm_ls
+}
+
+. ../../../nvm.sh
+
+nvm_ls_current() {
+  echo "CURRENT!"
+  return 7
+}
+
+OUTPUT="$(nvm_version current)"
+EXPECTED_OUTPUT="CURRENT!"
+EXIT_CODE="$(nvm_version current 2>&1 >/dev/null ; echo $?)"
+[ "_$OUTPUT" = "_$EXPECTED_OUTPUT" ] || die '"nvm_version current" did not return nvm_ls_current output'
+[ "_$EXIT_CODE" = "_7" ] || die '"nvm_version current" did not return nvm_ls_current exit code'
+
+OUTPUT="$(nvm_version)"
+EXPECTED_OUTPUT="CURRENT!"
+EXIT_CODE="$(nvm_version 2>&1 >/dev/null ; echo $?)"
+[ "_$OUTPUT" = "_$EXPECTED_OUTPUT" ] || die '"nvm_version" did not return nvm_ls_current output'
+[ "_$EXIT_CODE" = "_7" ] || die '"nvm_version" did not return nvm_ls_current exit code'
+
+nvm_ls() {
+  echo "line 1"
+  echo "line 2"
+  echo "pattern: $1"
+}
+
+[ "_$(nvm_version foo)" = "_pattern: foo" ] || die '"nvm_version foo" did not pass the pattern to "nvm_ls", or return the last line'
+
+nvm_ls() { echo "N/A"; }
+OUTPUT="$(nvm_version foo)"
+EXPECTED_OUTPUT="N/A"
+EXIT_CODE="$(nvm_version foo 2>&1 >/dev/null ; echo $?)"
+[ "_$OUTPUT" = "_$EXPECTED_OUTPUT" ] || die '"nvm_version" did not return N/A when nvm_ls returns N/A'
+[ "_$EXIT_CODE" = "_3" ] || die '"nvm_version" returning N/A did not exit code with code 3'
+
+nvm_ls() { echo; }
+OUTPUT="$(nvm_version foo)"
+EXPECTED_OUTPUT="N/A"
+EXIT_CODE="$(nvm_version foo 2>&1 >/dev/null ; echo $?)"
+[ "_$OUTPUT" = "_$EXPECTED_OUTPUT" ] || die '"nvm_version" did not return N/A when nvm_ls returns nothing'
+[ "_$EXIT_CODE" = "_3" ] || die '"nvm_version" returning N/A did not exit code with code 3'
diff --git "a/test/slow/nvm use/Running \"nvm use iojs\" uses latest io.js version" "b/test/slow/nvm use/Running \"nvm use iojs\" uses latest io.js version"
new file mode 100755
index 0000000..5b867f3
--- /dev/null
+++ "b/test/slow/nvm use/Running \"nvm use iojs\" uses latest io.js version"	
@@ -0,0 +1,14 @@
+#!/bin/sh
+
+die () { echo $@ ; exit 1; }
+
+. ../../../nvm.sh
+
+nvm deactivate 2>&1 >/dev/null || die 'deactivate failed'
+
+nvm use iojs || die 'nvm use iojs failed'
+OUTPUT="$(nvm current)"
+EXPECTED_OUTPUT="iojs-v1.0.1"
+
+[ "_$OUTPUT" = "_$EXPECTED_OUTPUT" ] \
+  || die "'nvm use iojs' + 'nvm current' did not output '$EXPECTED_OUTPUT'; got '$OUTPUT'"
diff --git "a/test/slow/nvm use/Running \"nvm use node\" uses latest stable node version" "b/test/slow/nvm use/Running \"nvm use node\" uses latest stable node version"
new file mode 100755
index 0000000..3514256
--- /dev/null
+++ "b/test/slow/nvm use/Running \"nvm use node\" uses latest stable node version"	
@@ -0,0 +1,14 @@
+#!/bin/sh
+
+die () { echo $@ ; exit 1; }
+
+. ../../../nvm.sh
+
+nvm deactivate 2>&1 >/dev/null || die 'deactivate failed'
+
+nvm use node || die 'nvm use node failed'
+OUTPUT="$(nvm current)"
+EXPECTED_OUTPUT="$(nvm_version stable)"
+
+[ "_$OUTPUT" = "_$EXPECTED_OUTPUT" ] \
+  || die "'nvm use node' + 'nvm current' did not output '$EXPECTED_OUTPUT'; got '$OUTPUT'"
diff --git a/test/slow/nvm use/setup_dir b/test/slow/nvm use/setup_dir
new file mode 100755
index 0000000..a3ab0f7
--- /dev/null
+++ b/test/slow/nvm use/setup_dir	
@@ -0,0 +1,16 @@
+#!/bin/sh
+
+. ../../../nvm.sh
+
+mkdir -p ../../../.nvm_use_bak
+if [ -d "../../../v*" ]; then
+  mv "../../../v*" ../../../.nvm_use_bak/
+fi
+
+for VERSION in "0.8.7" "0.9.1" "0.10.1" "0.11.1"; do
+  nvm install "v$VERSION"
+done
+
+for VERSION in "1.0.0" "1.0.1"; do
+  nvm install "iojs-v$VERSION"
+done
diff --git a/test/slow/nvm use/teardown_dir b/test/slow/nvm use/teardown_dir
new file mode 100755
index 0000000..eeda337
--- /dev/null
+++ b/test/slow/nvm use/teardown_dir	
@@ -0,0 +1,16 @@
+#!/bin/sh
+
+. ../../../nvm.sh
+
+for VERSION in "0.8.7" "0.9.1" "0.10.1" "0.11.1"; do
+  nvm uninstall "$VERSION"
+done
+
+for VERSION in "1.0.0" "1.0.1"; do
+  nvm uninstall "iojs-v$VERSION"
+done
+
+if [ -d ../../../.nvm_use_bak/* ]; then
+  mv ../../../.nvm_use_bak/* ../../../
+fi
+rmdir ../../../.nvm_use_bak