diff --git a/data/generated.go b/data/generated.go
index 2eea4d2..37680fa 100644
--- a/data/generated.go
+++ b/data/generated.go
@@ -209,6 +209,9 @@ func isCompiledCoffeeScript(path, ext string, content []byte) bool {
 
 	firstLine := getFirstLine(content)
 	lastLines := getLines(content, -2)
+	if len(lastLines) < 2 {
+		return false
+	}
 
 	if string(firstLine) == "(function() {" &&
 		string(lastLines[1]) == "}).call(this);" &&
@@ -675,9 +678,11 @@ func isGeneratedHTML(_, ext string, content []byte) bool {
 	lines := getLines(content, 30)
 
 	// Pkgdown
-	for _, l := range lines[:2] {
-		if bytes.Contains(l, []byte("<!-- Generated by pkgdown: do not edit by hand -->")) {
-			return true
+	if len(lines) >= 2 {
+		for _, l := range lines[:2] {
+			if bytes.Contains(l, []byte("<!-- Generated by pkgdown: do not edit by hand -->")) {
+				return true
+			}
 		}
 	}