diff --git a/.travis.yml b/.travis.yml
index 392b52e..e8a4731 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -7,4 +7,8 @@ services:
 
 before_install:
   - docker build -t eficode/wait-for .
+
+script:
+  - npm install
+  - ./run_tests.sh
   - docker run eficode/wait-for
diff --git a/Dockerfile b/Dockerfile
index 412d8e1..f636844 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -8,4 +8,5 @@ WORKDIR /app
 COPY . /app
 RUN npm install
 
-CMD ./node_modules/.bin/bats wait-for.bats
+# On launch, run the test suite via npm
+CMD npm test
diff --git a/README.md b/README.md
index f1956f7..ca2d3a9 100644
--- a/README.md
+++ b/README.md
@@ -9,8 +9,9 @@ When using this tool, you only need to pick the `wait-for` file as part of your
 ## Usage
 
 ```
-./wait-for host:port [-t timeout] [-- command args]
+wait-for host:port [-t timeout] [-- command args]
   -q | --quiet                        Do not output any status messages
+  -l | --loose                        Execute subcommand even if the test times out
   -t TIMEOUT | --timeout=timeout      Timeout in seconds, zero for no timeout
   -- COMMAND ARGS                     Execute command with args after the test finishes
 ```
@@ -21,11 +22,19 @@ To check if [eficode.com](https://eficode.com) is available:
 
 ```
 $ ./wait-for www.eficode.com:80 -- echo "Eficode site is up"
-
-Connection to www.eficode.com port 80 [tcp/http] succeeded!
 Eficode site is up
 ```
 
+The subcommand will be executed regardless if the service is up or not. If you wish to execute the subcommand only if the service is up, add the --strict argument. In this example, we will test port 81 on www.google.com which will fail:
+
+```
+$ ./wait-for www.google.com:81 --timeout=1 -- echo "google is up"
+Operation timed out
+$ ./wait-for www.google.com:81 --timeout=1 --loose -- echo "waited for google"
+Operation timed out
+waited for google
+```
+
 To wait for database container to become available:
 
 
diff --git a/package.json b/package.json
index 977ac4a..7aea0e7 100644
--- a/package.json
+++ b/package.json
@@ -2,7 +2,7 @@
   "name": "wait-for",
   "version": "0.1.0",
   "scripts": {
-    "test": "./node_modules/.bin/bats wait-for.bats"
+    "test": "./run_tests.sh"
   },
   "dependencies": {
     "bats": "^0.4.2"
diff --git a/run_tests.sh b/run_tests.sh
new file mode 100755
index 0000000..7bc5257
--- /dev/null
+++ b/run_tests.sh
@@ -0,0 +1,8 @@
+#!/bin/sh
+
+# Although it would be possible to just call this directly from the Dockerfile,
+# centralizing tests in this file allows both the docker container and the
+# CI machine to run the same set of tests for an additional datapoint --
+# which gives a better chance of turning up POSIX noncompliance
+
+./node_modules/.bin/bats wait-for.bats
diff --git a/wait-for b/wait-for
index ddfc39e..3b2241c 100755
--- a/wait-for
+++ b/wait-for
@@ -1,39 +1,71 @@
 #!/bin/sh
 
+OLD_TIMEOUT=$TIMEOUT
+OLD_QUIET=$QUIET
+OLD_PORT=$PORT
+OLD_HOST=$HOST
+OLD_LOOSE=$LOOSE
+
 TIMEOUT=15
 QUIET=0
+LOOSE=0
+
+if ! which nc >/dev/null; then
+  echo "Netcat is not installed. This script requires netcat to work correctly."
+  exit 1
+fi
 
 echoerr() {
   if [ "$QUIET" -ne 1 ]; then printf "%s\n" "$*" 1>&2; fi
 }
 
+conditionally_output() {
+  if [ "$QUIET" -ne 1 ]; then
+    "$@"
+  else
+    "$@" > /dev/null 2>&1
+  fi
+}
+
 usage() {
   exitcode="$1"
   cat << USAGE >&2
 Usage:
-  $cmdname host:port [-t timeout] [-- command args]
+  $(basename $0) host:port [-t timeout] [-- command args]
   -q | --quiet                        Do not output any status messages
+  -l | --loose                        Execute subcommand even if the test times out
   -t TIMEOUT | --timeout=timeout      Timeout in seconds, zero for no timeout
   -- COMMAND ARGS                     Execute command with args after the test finishes
 USAGE
   exit "$exitcode"
 }
 
+test_connection() {
+  conditionally_output echo "Testing connection to $1:$2..."
+
+  # force a 1-second timeout on darwin (https://stackoverflow.com/a/20460402/2063546)
+  # POSIX-compliant string inclusion test https://stackoverflow.com/a/8811800/2063546
+  if [ "${OSTYPE#*darwin*}" != "$OSTYPE" ] ; then
+    conditionally_output nc -z -w 1 -G 1 "$1" "$2"
+  else
+    conditionally_output nc -z -w 1 "$1" "$2"
+  fi
+}
+
 wait_for() {
+  local result
   for i in `seq $TIMEOUT` ; do
-    nc -z "$HOST" "$PORT" > /dev/null 2>&1
-    
+    # use a 1-second timeout, but still sleep 0.1 seconds after just to be safe
+    test_connection "$HOST" "$PORT"
     result=$?
-    if [ $result -eq 0 ] ; then
-      if [ $# -gt 0 ] ; then
-        exec "$@"
-      fi
-      exit 0
-    fi
+    if [ $result -eq 0 ] ; then break ; fi
     sleep 1
   done
-  echo "Operation timed out" >&2
-  exit 1
+  [ $result -ne 0 ] && echoerr "Operation timed out"
+  if [ $result -eq 0 -o $LOOSE -eq 1 -a $# -gt 0 ] ; then
+    TIMEOUT=$OLD_TIMEOUT QUIET=$OLD_QUIET PORT=$OLD_PORT HOST=$OLD_HOST LOOSE=$OLD_LOOSE exec "$@"
+  fi
+  exit $result
 }
 
 while [ $# -gt 0 ]
@@ -48,6 +80,10 @@ do
     QUIET=1
     shift 1
     ;;
+    -l | --loose)
+    LOOSE=1
+    shift 1
+    ;;
     -t)
     TIMEOUT="$2"
     if [ "$TIMEOUT" = "" ]; then break; fi
diff --git a/wait-for.bats b/wait-for.bats
index cbea6a4..a95f889 100644
--- a/wait-for.bats
+++ b/wait-for.bats
@@ -1,8 +1,8 @@
 #!/usr/bin/env bats
 
-@test "google should be immediately found" {
-  run ./wait-for google.com:80 -- echo 'success'
-  
+@test "google should be immediately found, no output other than our own" {
+  run ./wait-for -q google.com:80 -- echo 'success'
+
   [ "$output" = "success" ]
 }
 
@@ -12,3 +12,27 @@
   [ "$status" -ne 0 ]
   [ "$output" != "success" ]
 }
+
+@test "nonexistent server should start command if loose option is specified" {
+  run ./wait-for -q -t 1 -l noserver:9999 -- echo 'passable' 2>&1
+
+  [ "$status" -eq 0 ]
+
+  [ "$output" = "passable" ]
+}
+
+@test "preserve existing environment variables" {
+  TIMEOUT=mytimeout
+  QUIET=myquiet
+  HOST=myhost
+  PORT=myport
+  LOOSE=myloose
+
+  run ./wait-for google.com:80 -- echo 'success'
+
+  [ "$(echo $TIMEOUT)" = 'mytimeout' ]
+  [ "$(echo $QUIET)" = 'myquiet' ]
+  [ "$(echo $HOST)" = 'myhost' ]
+  [ "$(echo $PORT)" = 'myport' ]
+  [ "$(echo $LOOSE)" = 'myloose' ]
+}