diff --git a/src/arch/arm/insts/pseudo.cc b/src/arch/arm/insts/pseudo.cc
index 3d017c1857..0402071255 100644
--- a/src/arch/arm/insts/pseudo.cc
+++ b/src/arch/arm/insts/pseudo.cc
@@ -116,6 +116,7 @@ FailUnimplemented::FailUnimplemented(const char *_mnemonic,
     // don't call execute() (which panics) if we're on a
     // speculative path
     flags[IsNonSpeculative] = true;
+    flags[IsInvalid] = true;
 }
 
 FailUnimplemented::FailUnimplemented(const char *_mnemonic,
@@ -127,6 +128,7 @@ FailUnimplemented::FailUnimplemented(const char *_mnemonic,
     // don't call execute() (which panics) if we're on a
     // speculative path
     flags[IsNonSpeculative] = true;
+    flags[IsInvalid] = true;
 }
 
 Fault
diff --git a/src/arch/mips/isa/formats/unimp.isa b/src/arch/mips/isa/formats/unimp.isa
index 198e20b820..776698f291 100644
--- a/src/arch/mips/isa/formats/unimp.isa
+++ b/src/arch/mips/isa/formats/unimp.isa
@@ -49,6 +49,7 @@ output header {{
             // don't call execute() (which panics) if we're on a
             // speculative path
             flags[IsNonSpeculative] = true;
+            flags[IsInvalid] = true;
         }
 
         Fault execute(ExecContext *, trace::InstRecord *) const override;
diff --git a/src/arch/power/isa/formats/unimp.isa b/src/arch/power/isa/formats/unimp.isa
index 9e1e46051b..5e9579fa5e 100644
--- a/src/arch/power/isa/formats/unimp.isa
+++ b/src/arch/power/isa/formats/unimp.isa
@@ -51,6 +51,7 @@ output header {{
             // don't call execute() (which panics) if we're on a
             // speculative path
             flags[IsNonSpeculative] = true;
+            flags[IsInvalid] = true;
         }
 
         Fault execute(ExecContext *, trace::InstRecord *) const override;
diff --git a/src/arch/sparc/insts/unimp.hh b/src/arch/sparc/insts/unimp.hh
index 9eda012182..8609823382 100644
--- a/src/arch/sparc/insts/unimp.hh
+++ b/src/arch/sparc/insts/unimp.hh
@@ -59,7 +59,9 @@ class FailUnimplemented : public SparcStaticInst
     /// Constructor
     FailUnimplemented(const char *_mnemonic, ExtMachInst _machInst) :
             SparcStaticInst(_mnemonic, _machInst, No_OpClass)
-    {}
+    {
+        flags[IsInvalid] = true;
+    }
 
     Fault
     execute(ExecContext *xc, trace::InstRecord *traceData) const override
diff --git a/src/arch/x86/isa/formats/unimp.isa b/src/arch/x86/isa/formats/unimp.isa
index 2950f55891..e43ed00764 100644
--- a/src/arch/x86/isa/formats/unimp.isa
+++ b/src/arch/x86/isa/formats/unimp.isa
@@ -58,6 +58,7 @@ output header {{
             // don't call execute() (which panics) if we're on a
             // speculative path
             flags[IsNonSpeculative] = true;
+            flags[IsInvalid] = true;
         }
 
         Fault execute(ExecContext *, trace::InstRecord *) const override;