diff --git a/src/emucore/CartBUS.cxx b/src/emucore/CartBUS.cxx
index fa40667b2..f3799d67b 100644
--- a/src/emucore/CartBUS.cxx
+++ b/src/emucore/CartBUS.cxx
@@ -64,9 +64,10 @@ CartridgeBUS::CartridgeBUS(const BytePtr& image, uInt32 size,
   myDisplayImage = myBUSRAM + DSRAM;
 
   // Create Thumbulator ARM emulator
+  string prefix = settings.getBool("dev.settings") ? "plr." : "dev.";
   myThumbEmulator = make_unique<Thumbulator>(
     reinterpret_cast<uInt16*>(myImage), reinterpret_cast<uInt16*>(myBUSRAM),
-    settings.getBool("thumb.trapfatal"), Thumbulator::ConfigureFor::BUS, this
+    settings.getBool(prefix + "thumb.trapfatal"), Thumbulator::ConfigureFor::BUS, this
   );
 
   setInitialState();
diff --git a/src/emucore/CartCDF.cxx b/src/emucore/CartCDF.cxx
index 1e7268ee0..599cc9bc8 100644
--- a/src/emucore/CartCDF.cxx
+++ b/src/emucore/CartCDF.cxx
@@ -67,9 +67,10 @@ CartridgeCDF::CartridgeCDF(const BytePtr& image, uInt32 size,
   setVersion();
 
   // Create Thumbulator ARM emulator
+  string prefix = settings.getBool("dev.settings") ? "plr." : "dev.";
   myThumbEmulator = make_unique<Thumbulator>(
     reinterpret_cast<uInt16*>(myImage), reinterpret_cast<uInt16*>(myCDFRAM),
-    settings.getBool("thumb.trapfatal"), myVersion ?
+    settings.getBool(prefix + "thumb.trapfatal"), myVersion ?
     Thumbulator::ConfigureFor::CDF1 : Thumbulator::ConfigureFor::CDF, this);
 
   setInitialState();
diff --git a/src/emucore/CartDPCPlus.cxx b/src/emucore/CartDPCPlus.cxx
index b03b0bf1e..f6a3ab258 100644
--- a/src/emucore/CartDPCPlus.cxx
+++ b/src/emucore/CartDPCPlus.cxx
@@ -53,10 +53,11 @@ CartridgeDPCPlus::CartridgeDPCPlus(const BytePtr& image, uInt32 size,
   myFrequencyImage = myDisplayImage + 0x1000;
 
   // Create Thumbulator ARM emulator
+  string prefix = settings.getBool("dev.settings") ? "plr." : "dev.";
   myThumbEmulator = make_unique<Thumbulator>
       (reinterpret_cast<uInt16*>(myImage),
        reinterpret_cast<uInt16*>(myDPCRAM),
-       settings.getBool("thumb.trapfatal"),
+       settings.getBool(prefix + "thumb.trapfatal"),
        Thumbulator::ConfigureFor::DPCplus,
        this);