diff --git a/index_test.go b/index_test.go
index af9cff9..576e863 100644
--- a/index_test.go
+++ b/index_test.go
@@ -1790,3 +1790,16 @@
 		t.Fatalf("got MatchLength %d want %d", fr.MatchLength, len(content))
 	}
 }
+
+func TestIsText(t *testing.T) {
+	for _, text := range []string{"", "simple ascii", "símplé unicödé", "\uFEFFwith utf8 'bom'", "with \uFFFD unicode replacement char"} {
+		if !IsText([]byte(text)) {
+			t.Errorf("IsText(%q) is false", text)
+		}
+	}
+	for _, text := range []string{"zero\x00byte", "high\xEFbyte"} {
+		if IsText([]byte(text)) {
+			t.Errorf("IsText(%q) is true", text)
+		}
+	}
+}
diff --git a/indexbuilder.go b/indexbuilder.go
index 9475d58..7895235 100644
--- a/indexbuilder.go
+++ b/indexbuilder.go
@@ -278,7 +278,7 @@
 		}
 
 		r, sz := utf8.DecodeRune(content)
-		if r == utf8.RuneError {
+		if r == utf8.RuneError && sz < 2 {
 			return false
 		}
 		content = content[sz:]