diff --git a/nvm.sh b/nvm.sh
index 011c664..184440a 100644
--- a/nvm.sh
+++ b/nvm.sh
@@ -289,6 +289,13 @@ nvm_version_path() {
 nvm_ensure_version_installed() {
   local PROVIDED_VERSION
   PROVIDED_VERSION="${1-}"
+  if [ "${PROVIDED_VERSION}" = 'system' ]; then
+    if nvm_has_system_iojs || nvm_has_system_node; then
+      return 0
+    fi
+    nvm_err "N/A: no system version of node/io.js is installed."
+    return 1
+  fi
   local LOCAL_VERSION
   local EXIT_CODE
   LOCAL_VERSION="$(nvm_version "${PROVIDED_VERSION}")"
diff --git a/test/fast/Unit tests/nvm_ensure_version_installed b/test/fast/Unit tests/nvm_ensure_version_installed
index 4e167ed..e819657 100755
--- a/test/fast/Unit tests/nvm_ensure_version_installed	
+++ b/test/fast/Unit tests/nvm_ensure_version_installed	
@@ -3,6 +3,7 @@
 die () { echo "$@" ; cleanup ; exit 1; }
 cleanup () {
   rm -rf "$(nvm_version_path v0.1.2)"
+  unset -f nvm_has_system_node nvm_has_system_iojs
 }
 
 \. ../../../nvm.sh
@@ -31,4 +32,31 @@ You need to run "nvm install iojs" to install it before using it.'
 [ "_$OUTPUT" = "_$EXPECTED_OUTPUT" ] || die "expected 'nvm_ensure_version_installed iojs' to give $EXPECTED_OUTPUT, got $OUTPUT"
 [ "_$EXIT_CODE" = "_1" ] || die "expected 'nvm_ensure_version_installed iojs' to exit with 1, got $EXIT_CODE"
 
+nvm_has_system_node() { return 1; }
+nvm_has_system_iojs() { return 1; }
+
+OUTPUT="$(nvm_ensure_version_installed system 2>&1)"
+EXIT_CODE=$?
+EXPECTED_OUTPUT='N/A: no system version of node/io.js is installed.'
+[ "_$OUTPUT" = "_$EXPECTED_OUTPUT" ] || die "expected 'nvm_ensure_version_installed system' with neither installed to give $EXPECTED_OUTPUT, got $OUTPUT"
+[ "_$EXIT_CODE" = "_1" ] || die "expected 'nvm_ensure_version_installed system' with neither installed to exit with 1, got $EXIT_CODE"
+
+nvm_has_system_node() { return 0; }
+nvm_has_system_iojs() { return 1; }
+
+OUTPUT="$(nvm_ensure_version_installed system 2>&1)"
+EXIT_CODE=$?
+EXPECTED_OUTPUT=''
+[ "_$OUTPUT" = "_$EXPECTED_OUTPUT" ] || die "expected 'nvm_ensure_version_installed system' with node installed to give $EXPECTED_OUTPUT, got $OUTPUT"
+[ "_$EXIT_CODE" = "_0" ] || die "expected 'nvm_ensure_version_installed system' with node installed to exit with 0, got $EXIT_CODE"
+
+nvm_has_system_node() { return 1; }
+nvm_has_system_iojs() { return 0; }
+
+OUTPUT="$(nvm_ensure_version_installed system 2>&1)"
+EXIT_CODE=$?
+EXPECTED_OUTPUT=''
+[ "_$OUTPUT" = "_$EXPECTED_OUTPUT" ] || die "expected 'nvm_ensure_version_installed system' with iojs installed to give $EXPECTED_OUTPUT, got $OUTPUT"
+[ "_$EXIT_CODE" = "_0" ] || die "expected 'nvm_ensure_version_installed system' with iojs installed to exit with 0, got $EXIT_CODE"
+
 cleanup