diff --git a/qemu/target-arm/internals.h b/qemu/target-arm/internals.h
index 3d69f532..57239452 100644
--- a/qemu/target-arm/internals.h
+++ b/qemu/target-arm/internals.h
@@ -349,6 +349,12 @@ static inline uint32_t syn_breakpoint(int same_el)
         | ARM_EL_IL | 0x22;
 }
 
+static inline uint32_t syn_wfx(int cv, int cond, int ti)
+{
+    return (EC_WFX_TRAP << ARM_EL_EC_SHIFT) |
+           (cv << 24) | (cond << 20) | ti;
+}
+
 /* Update a QEMU watchpoint based on the information the guest has set in the
  * DBGWCR<n>_EL1 and DBGWVR<n>_EL1 registers.
  */