diff --git a/src/emucore/CartELF.cxx b/src/emucore/CartELF.cxx
index 303ec050e..be2311756 100644
--- a/src/emucore/CartELF.cxx
+++ b/src/emucore/CartELF.cxx
@@ -456,7 +456,7 @@ void CartridgeELF::jumpToMain()
     .setRegister(0, sp )
     .setRegister(13, sp)
     .setRegister(14, RETURN_ADDR_MAIN)
-    .setRegister(15, myArmEntrypoint);
+    .setPc(myArmEntrypoint);
 }
 
 void CartridgeELF::runArm()
diff --git a/src/emucore/CortexM0.cxx b/src/emucore/CortexM0.cxx
index 702ffe081..63c5bac54 100644
--- a/src/emucore/CortexM0.cxx
+++ b/src/emucore/CortexM0.cxx
@@ -553,10 +553,6 @@ CortexM0& CortexM0::mapRegionCode(uInt32 pageBase,
   region.access.accessCode.backingStore = backingStore;
   region.access.accessCode.ops = static_cast<uInt8*>(std::malloc((pageCount * PAGE_SIZE) >> 1));
 
-  for (size_t i = 0; i < pageCount * PAGE_SIZE; i += 2)
-    region.access.accessCode.ops[i >> 1] =
-      decodeInstructionWord(READ16(backingStore, i));
-
   return *this;
 }
 
@@ -583,9 +579,16 @@ CortexM0& CortexM0::reset()
   reg_norm.fill(0);
   znFlags = cFlag = vFlag = 0;
 
+  recompileCodeRegions();
+
   return *this;
 }
 
+CortexM0& CortexM0::setPc(uInt32 pc)
+{
+  return setRegister(15, (pc & ~1) + 2);
+}
+
 CortexM0& CortexM0::setRegister(uInt8 regno, uInt32 value)
 {
   write_register(regno, value);
@@ -610,7 +613,7 @@ CortexM0::err_t CortexM0::run(uInt32 maxCycles, uInt32& cycles)
 
     uInt16 inst;
     uInt8 op;
-    err_t err = fetch16(pc -2, inst, op);
+    err_t err = fetch16(pc - 2, inst, op);
 
     if (err) return err;
 
@@ -650,6 +653,17 @@ CortexM0::MemoryRegion& CortexM0::setupMapping(uInt32 pageBase, uInt32 pageCount
   return region;
 }
 
+void CortexM0::recompileCodeRegions()
+{
+  for (const auto& region: myRegions) {
+    if (region.type != MemoryRegionType::directCode) continue;
+
+    for (size_t i = 0; i < region.size; i += 2)
+      region.access.accessCode.ops[i >> 1] =
+        decodeInstructionWord(READ16(region.access.accessCode.backingStore, i));
+  }
+}
+
 CortexM0::err_t CortexM0::read32(uInt32 address, uInt32& value)
 {
   if (address & 0x03) return errIntrinsic(ERR_ACCESS_ALIGNMENT_FAULT, address);
@@ -1176,7 +1190,7 @@ CortexM0::err_t CortexM0::execute(uInt16 inst, uInt8 op)
     }
 
     case Op::bkpt:
-      return errIntrinsic(ERR_BKPT, read_register(15) - 2);
+      return errIntrinsic(ERR_BKPT, read_register(15) - 4);
 
     //BL/BLX(1) variants
     // (bl, blx_thumb)
@@ -1216,7 +1230,7 @@ CortexM0::err_t CortexM0::execute(uInt16 inst, uInt8 op)
         write_register(15, rc);
         return ERR_NONE;
       }
-      else return errIntrinsic(ERR_INVALID_OPERATING_MODE, read_register(15) - 2);
+      else return errIntrinsic(ERR_INVALID_OPERATING_MODE, read_register(15) - 4);
     }
 
     //BX
@@ -1233,7 +1247,7 @@ CortexM0::err_t CortexM0::execute(uInt16 inst, uInt8 op)
         write_register(15, rc);
         return ERR_NONE;
       }
-      else return errIntrinsic(ERR_INVALID_OPERATING_MODE, read_register(15) - 2);
+      else return errIntrinsic(ERR_INVALID_OPERATING_MODE, read_register(15) - 4);
     }
 
     //CMN
@@ -1864,11 +1878,6 @@ CortexM0::err_t CortexM0::execute(uInt16 inst, uInt8 op)
         rc = read_register(14);
         const err_t err = write32(rd, rc);
         if (err) return err;
-
-        if((rc & 1) == 0)
-        {
-          return errIntrinsic(ERR_INVALID_OPERATING_MODE, read_register(15) - 2);
-        }
       }
       write_register(13, sp);
       return ERR_NONE;
@@ -1966,7 +1975,7 @@ CortexM0::err_t CortexM0::execute(uInt16 inst, uInt8 op)
 #ifndef UNSAFE_OPTIMIZATIONS
     //SETEND
     case Op::setend: {
-      return errIntrinsic(ERR_UNIMPLEMENTED_INST, read_register(15) - 2);
+      return errIntrinsic(ERR_UNIMPLEMENTED_INST, read_register(15) - 4);
     }
 #endif
 
@@ -2235,6 +2244,6 @@ CortexM0::err_t CortexM0::execute(uInt16 inst, uInt8 op)
     }
 
     default:
-      return errIntrinsic(ERR_UNDEFINED_INST, read_register(15) - 2);
+      return errIntrinsic(ERR_UNDEFINED_INST, read_register(15) - 4);
   }
 }
diff --git a/src/emucore/CortexM0.hxx b/src/emucore/CortexM0.hxx
index 81c271504..81224b70c 100644
--- a/src/emucore/CortexM0.hxx
+++ b/src/emucore/CortexM0.hxx
@@ -104,6 +104,7 @@ class CortexM0
     CortexM0& mapDefault(BusTransactionDelegate* delegate);
 
     CortexM0& reset();
+    CortexM0& setPc(uInt32 pc);
     CortexM0& setRegister(uInt8 regno, uInt32 value);
     uInt32 getRegister(uInt32 regno);
 
@@ -168,6 +169,8 @@ class CortexM0
     MemoryRegion& setupMapping(uInt32 pageBase, uInt32 pageCount,
                                bool readOnly, MemoryRegionType type);
 
+    void recompileCodeRegions();
+
     err_t fetch16(uInt32 address, uInt16& value, uInt8& op);
 
     void do_cvflag(uInt32 a, uInt32 b, uInt32 c);