diff --git a/internal/phpgrep/main.go b/internal/phpgrep/main.go
index 2557988..4207921 100644
--- a/internal/phpgrep/main.go
+++ b/internal/phpgrep/main.go
@@ -30,6 +30,9 @@ type arguments struct {
 	cpuProfile string
 	memProfile string
 
+	phpFileExt     string
+	phpFileExtList []string
+
 	targets        string
 	pattern        string
 	filters        []string
@@ -168,6 +171,8 @@ Supported command-line flags:
 		`exclude files or directories by regexp pattern`)
 	flag.StringVar(&args.excludeResults, "exclude-results", "",
 		`exclude the results listed in the file`)
+	flag.StringVar(&args.phpFileExt, "php-ext", "php,php5,inc,phtml",
+		`a comma-separated list of extensions to scan`)
 
 	flag.StringVar(&args.progressMode, "progress", "update",
 		`progress printing mode: "update", "append" or "none"`)
diff --git a/internal/phpgrep/program.go b/internal/phpgrep/program.go
index d916cf3..ec6a9f7 100644
--- a/internal/phpgrep/program.go
+++ b/internal/phpgrep/program.go
@@ -90,6 +90,11 @@ func (p *program) validateFlags() error {
 	if p.args.limit == 0 || p.args.limit > maxLimit {
 		p.args.limit = maxLimit
 	}
+
+	for _, e := range strings.Split(p.args.phpFileExt, ",") {
+		p.args.phpFileExtList = append(p.args.phpFileExtList, "."+strings.TrimSpace(e))
+	}
+
 	return nil
 }
 
@@ -353,12 +358,7 @@ func (p *program) executePattern() error {
 }
 
 func (p *program) walkTarget(target string, filenameQueue chan<- string, ticker *time.Ticker) error {
-	phpExtensions := []string{
-		".php",
-		".php5",
-		".inc",
-		".phtml",
-	}
+	phpExtensions := p.args.phpFileExtList
 	isPHPFile := func(name string) bool {
 		for _, ext := range phpExtensions {
 			if strings.HasSuffix(name, ext) {