diff --git a/post-processor/shell-local/post-processor.go b/post-processor/shell-local/post-processor.go
index 1096d3a7f..afe4eb486 100644
--- a/post-processor/shell-local/post-processor.go
+++ b/post-processor/shell-local/post-processor.go
@@ -7,6 +7,7 @@ import (
 	"io/ioutil"
 	"log"
 	"os"
+	"sort"
 	"strings"
 
 	"github.com/mitchellh/packer/common"
@@ -112,17 +113,11 @@ func (p *PostProcessor) Configure(raws ...interface{}) error {
 	}
 
 	// Do a check for bad environment variables, such as '=foo', 'foobar'
-	for idx, kv := range p.config.Vars {
+	for _, kv := range p.config.Vars {
 		vs := strings.SplitN(kv, "=", 2)
 		if len(vs) != 2 || vs[0] == "" {
 			errs = packer.MultiErrorAppend(errs,
 				fmt.Errorf("Environment variable not in format 'key=value': %s", kv))
-		} else {
-			// Replace single quotes so they parse
-			vs[1] = strings.Replace(vs[1], "'", `'"'"'`, -1)
-
-			// Single quote env var values
-			p.config.Vars[idx] = fmt.Sprintf("%s='%s'", vs[0], vs[1])
 		}
 	}
 
@@ -166,18 +161,13 @@ func (p *PostProcessor) PostProcess(ui packer.Ui, artifact packer.Artifact) (pac
 		tf.Close()
 	}
 
-	// Build our variables up by adding in the build name and builder type
-	envVars := make([]string, len(p.config.Vars)+2)
-	envVars[0] = fmt.Sprintf("PACKER_BUILD_NAME='%s'", p.config.PackerBuildName)
-	envVars[1] = fmt.Sprintf("PACKER_BUILDER_TYPE='%s'", p.config.PackerBuilderType)
-	copy(envVars[2:], p.config.Vars)
+	// Create environment variables to set before executing the command
+	flattenedEnvVars := p.createFlattenedEnvVars()
 
 	for _, script := range scripts {
-		// Flatten the environment variables
-		flattendVars := strings.Join(envVars, " ")
 
 		p.config.ctx.Data = &ExecuteCommandTemplate{
-			Vars:   flattendVars,
+			Vars:   flattenedEnvVars,
 			Script: script,
 		}
 
@@ -210,3 +200,33 @@ func (p *PostProcessor) PostProcess(ui packer.Ui, artifact packer.Artifact) (pac
 
 	return artifact, true, nil
 }
+
+func (p *PostProcessor) createFlattenedEnvVars() (flattened string) {
+	flattened = ""
+	envVars := make(map[string]string)
+
+	// Always available Packer provided env vars
+	envVars["PACKER_BUILD_NAME"] = fmt.Sprintf("%s", p.config.PackerBuildName)
+	envVars["PACKER_BUILDER_TYPE"] = fmt.Sprintf("%s", p.config.PackerBuilderType)
+
+	// Split vars into key/value components
+	for _, envVar := range p.config.Vars {
+		keyValue := strings.SplitN(envVar, "=", 2)
+		// Store pair, replacing any single quotes in value so they parse
+		// correctly with required environment variable format
+		envVars[keyValue[0]] = strings.Replace(keyValue[1], "'", `'"'"'`, -1)
+	}
+
+	// Create a list of env var keys in sorted order
+	var keys []string
+	for k := range envVars {
+		keys = append(keys, k)
+	}
+	sort.Strings(keys)
+
+	// Re-assemble vars surrounding value with single quotes and flatten
+	for _, key := range keys {
+		flattened += fmt.Sprintf("%s='%s' ", key, envVars[key])
+	}
+	return
+}