diff --git a/runtime/vm/compiler/assembler/assembler_dbc.cc b/runtime/vm/compiler/assembler/assembler_dbc.cc
index 3465c38..a7643b6 100644
--- a/runtime/vm/compiler/assembler/assembler_dbc.cc
+++ b/runtime/vm/compiler/assembler/assembler_dbc.cc
@@ -75,6 +75,10 @@
   return Thread::Current()->zone()->PrintToString("R%d", reg);
 }
 
+const char* Assembler::FpuRegisterName(FpuRegister reg) {
+  return Thread::Current()->zone()->PrintToString("F%d", reg);
+}
+
 static int32_t EncodeJump(int32_t relative_pc) {
   return SimulatorBytecode::kJump | (relative_pc << 8);
 }
diff --git a/runtime/vm/compiler/assembler/assembler_dbc.h b/runtime/vm/compiler/assembler/assembler_dbc.h
index 09a5aa1..9787191 100644
--- a/runtime/vm/compiler/assembler/assembler_dbc.h
+++ b/runtime/vm/compiler/assembler/assembler_dbc.h
@@ -45,7 +45,7 @@
 
   static const char* RegisterName(Register reg);
 
-  static const char* FpuRegisterName(FpuRegister reg) { return "?"; }
+  static const char* FpuRegisterName(FpuRegister reg);
 
   static uword GetBreakInstructionFiller() { return SimulatorBytecode::kTrap; }
 
diff --git a/runtime/vm/deopt_instructions.h b/runtime/vm/deopt_instructions.h
index e2096b6..9270768 100644
--- a/runtime/vm/deopt_instructions.h
+++ b/runtime/vm/deopt_instructions.h
@@ -97,9 +97,9 @@
 
   double FpuRegisterValue(FpuRegister reg) const {
     ASSERT(FlowGraphCompiler::SupportsUnboxedDoubles());
+#if !defined(TARGET_ARCH_DBC)
     ASSERT(fpu_registers_ != NULL);
     ASSERT(reg >= 0);
-#if !defined(TARGET_ARCH_DBC)
     ASSERT(reg < kNumberOfFpuRegisters);
     return *reinterpret_cast<double*>(&fpu_registers_[reg]);
 #else