diff --git a/src/jobs.hpp b/src/jobs.hpp
index 99cd04f..cc3d50b 100644
--- a/src/jobs.hpp
+++ b/src/jobs.hpp
@@ -59,6 +59,11 @@ class KggTask {
         }
 
         auto qmc2 = QMC2::Create(ekey);
+        if (!qmc2) {
+            error(L"create qmc2 instance failed (ekey decode error?)");
+            fprintf(stderr, "%s\n", ekey.c_str());
+            return;
+        }
 
         std::string magic(4, 0);
         kgg_stream_in.seekg(offset_to_audio, std::ios::beg);