diff --git a/pkg/csource/csource_test.go b/pkg/csource/csource_test.go
index ece28cd9..3eec9979 100644
--- a/pkg/csource/csource_test.go
+++ b/pkg/csource/csource_test.go
@@ -4,6 +4,7 @@
 package csource
 
 import (
+	"bytes"
 	"fmt"
 	"io/ioutil"
 	"math/rand"
@@ -152,6 +153,11 @@ func TestSysTests(t *testing.T) {
 				if err != nil {
 					t.Fatalf("failed to read %v: %v", file, err)
 				}
+				// syz_mount_image tests are very large and this test takes too long.
+				// syz-imagegen that generates does some of this testing (Deserialize/SerializeForExec).
+				if bytes.Contains(data, []byte("# requires: manual")) {
+					continue
+				}
 				p, err := target.Deserialize(data, prog.Strict)
 				if err != nil {
 					t.Fatalf("failed to parse program %v: %v", file, err)