diff --git a/ondevice-signing/Keymaster.cpp b/ondevice-signing/Keymaster.cpp
index 267dec8..6cfb565 100644
--- a/ondevice-signing/Keymaster.cpp
+++ b/ondevice-signing/Keymaster.cpp
@@ -66,6 +66,9 @@
         }
     }
 
+    if (devToUse == nullptr) {
+        LOG(WARNING) << "Didn't find a keymaster to use.";
+    }
     mDevice = devToUse;
 
     return mDevice != nullptr;