diff --git a/plugin.go b/plugin.go
index bb643bb..70e53da 100644
--- a/plugin.go
+++ b/plugin.go
@@ -39,7 +39,7 @@ func pkValidate(config Config) *exec.Cmd {
 	}
 
 	for _, v := range config.VarFiles {
-		args = append(args, "-var-file", fmt.Sprintf("%s", v))
+		args = append(args, fmt.Sprintf("-var-file=%s", v))
 	}
 
 	for k, v := range config.Vars {
@@ -72,7 +72,7 @@ func pkBuild(config Config) *exec.Cmd {
 	}
 
 	for _, v := range config.VarFiles {
-		args = append(args, "-var-file", fmt.Sprintf("%s", v))
+		args = append(args, fmt.Sprintf("-var-file=%s", v))
 	}
 
 	for k, v := range config.Vars {
diff --git a/plugin_test.go b/plugin_test.go
index 4a6b535..913d603 100644
--- a/plugin_test.go
+++ b/plugin_test.go
@@ -35,7 +35,7 @@ func Test_pkValidate(t *testing.T) {
 					VarFiles: []string{"bar.json"},
 				},
 			},
-			want: exec.Command("packer", "validate", "-var-file", "bar.json", "-var", "foo=bar", "foo.json"),
+			want: exec.Command("packer", "validate", "-var-file=bar.json", "-var", "foo=bar", "foo.json"),
 		},
 		{
 			name: "add except only color flag",
@@ -89,7 +89,7 @@ func Test_pkBuild(t *testing.T) {
 					VarFiles: []string{"bar.json"},
 				},
 			},
-			want: exec.Command("packer", "build", "-var-file", "bar.json", "-var", "foo=bar", "foo.json"),
+			want: exec.Command("packer", "build", "-var-file=bar.json", "-var", "foo=bar", "foo.json"),
 		},
 		{
 			name: "add Parallel, Color and debug flag",