diff --git a/libunwind/src/DwarfInstructions.hpp b/libunwind/src/DwarfInstructions.hpp
index 18556c6f2d4b..b23e54739050 100644
--- a/libunwind/src/DwarfInstructions.hpp
+++ b/libunwind/src/DwarfInstructions.hpp
@@ -165,9 +165,10 @@ typename A::capability_t DwarfInstructions<A, R>::getSavedCapabilityRegister(
 #else
     break;
 #endif
+  case CFI_Parser<A>::kRegisterUndefined:
+    return _LIBUNWIND_UNDEF_CAPABILITY;
 
   case CFI_Parser<A>::kRegisterInCFADecrypt: // sparc64 specific
-  case CFI_Parser<A>::kRegisterUndefined:
   case CFI_Parser<A>::kRegisterUnused:
   case CFI_Parser<A>::kRegisterOffsetFromCFA:
     // FIX ME
diff --git a/libunwind/src/Registers.hpp b/libunwind/src/Registers.hpp
index 92b0b8b9bb9a..9eda92bc2d00 100644
--- a/libunwind/src/Registers.hpp
+++ b/libunwind/src/Registers.hpp
@@ -29,7 +29,9 @@ struct __attribute__((aligned(16))) fake_capability {
   char bytes[16];
 };
 typedef struct fake_capability fake_capability_t;
+#define _LIBUNWIND_UNDEF_CAPABILITY ((fake_capability_t){0})
 #else
+#define _LIBUNWIND_UNDEF_CAPABILITY 0
 // To keep CAPABILITIES_NOT_SUPPORT working in hybrid mode
 // TODO: remove
 typedef __uintcap_t fake_capability_t;