diff --git a/include/dynarmic/callbacks.h b/include/dynarmic/callbacks.h
index 09f7d40f..9e127717 100644
--- a/include/dynarmic/callbacks.h
+++ b/include/dynarmic/callbacks.h
@@ -29,7 +29,8 @@ struct UserCallbacks {
     bool (*IsReadOnlyMemory)(std::uint32_t vaddr);
 
     /// The intrepreter must execute only one instruction at PC.
-    void (*InterpreterFallback)(std::uint32_t pc, Jit* jit);
+    void (*InterpreterFallback)(std::uint32_t pc, Jit* jit, void* user_arg);
+    void* user_arg = nullptr;
 
     bool (*CallSVC)(std::uint32_t swi);
 
diff --git a/src/backend_x64/emit_x64.cpp b/src/backend_x64/emit_x64.cpp
index e79b0a7a..fbd669f9 100644
--- a/src/backend_x64/emit_x64.cpp
+++ b/src/backend_x64/emit_x64.cpp
@@ -2188,6 +2188,7 @@ void EmitX64::EmitTerminalInterpret(IR::Term::Interpret terminal, Arm::LocationD
 
     code->mov(code->ABI_PARAM1.cvt32(), terminal.next.PC());
     code->mov(code->ABI_PARAM2, reinterpret_cast<u64>(jit_interface));
+    code->mov(code->ABI_PARAM3, reinterpret_cast<u64>(cb.user_arg));
     code->mov(MJitStateReg(Arm::Reg::PC), code->ABI_PARAM1.cvt32());
     code->SwitchMxcsrOnExit();
     code->CallFunction(cb.InterpreterFallback);
diff --git a/tests/arm/fuzz_arm.cpp b/tests/arm/fuzz_arm.cpp
index 7a6a4854..e4ded4ca 100644
--- a/tests/arm/fuzz_arm.cpp
+++ b/tests/arm/fuzz_arm.cpp
@@ -56,7 +56,7 @@ static void MemoryWrite8(u32 vaddr, u8 value);
 static void MemoryWrite16(u32 vaddr, u16 value);
 static void MemoryWrite32(u32 vaddr, u32 value);
 static void MemoryWrite64(u32 vaddr, u64 value);
-static void InterpreterFallback(u32 pc, Dynarmic::Jit* jit);
+static void InterpreterFallback(u32 pc, Dynarmic::Jit* jit, void*);
 static Dynarmic::UserCallbacks GetUserCallbacks();
 
 static bool IsReadOnlyMemory(u32 vaddr) {
@@ -92,7 +92,7 @@ static void MemoryWrite64(u32 vaddr, u64 value){
     write_records.push_back({64, vaddr, value});
 }
 
-static void InterpreterFallback(u32 pc, Dynarmic::Jit* jit) {
+static void InterpreterFallback(u32 pc, Dynarmic::Jit* jit, void*) {
     ARMul_State interp_state{USER32MODE};
     interp_state.user_callbacks = GetUserCallbacks();
     interp_state.NumInstrsToExecute = 1;
diff --git a/tests/arm/fuzz_thumb.cpp b/tests/arm/fuzz_thumb.cpp
index df07df54..2231dc00 100644
--- a/tests/arm/fuzz_thumb.cpp
+++ b/tests/arm/fuzz_thumb.cpp
@@ -48,7 +48,7 @@ static void MemoryWrite8(u32 vaddr, u8 value);
 static void MemoryWrite16(u32 vaddr, u16 value);
 static void MemoryWrite32(u32 vaddr, u32 value);
 static void MemoryWrite64(u32 vaddr, u64 value);
-static void InterpreterFallback(u32 pc, Dynarmic::Jit* jit);
+static void InterpreterFallback(u32 pc, Dynarmic::Jit* jit, void*);
 static Dynarmic::UserCallbacks GetUserCallbacks();
 
 static bool IsReadOnlyMemory(u32 vaddr) {
@@ -84,7 +84,7 @@ static void MemoryWrite64(u32 vaddr, u64 value){
     write_records.push_back({64, vaddr, value});
 }
 
-static void InterpreterFallback(u32 pc, Dynarmic::Jit* jit) {
+static void InterpreterFallback(u32 pc, Dynarmic::Jit* jit, void*) {
     ARMul_State interp_state{USER32MODE};
     interp_state.user_callbacks = GetUserCallbacks();
     interp_state.NumInstrsToExecute = 1;
diff --git a/tests/arm/test_thumb_instructions.cpp b/tests/arm/test_thumb_instructions.cpp
index 5c96a688..8a238ff4 100644
--- a/tests/arm/test_thumb_instructions.cpp
+++ b/tests/arm/test_thumb_instructions.cpp
@@ -15,7 +15,7 @@
 static std::array<u16, 1024> code_mem{};
 
 static u32 MemoryRead32(u32 vaddr);
-static void InterpreterFallback(u32 pc, Dynarmic::Jit* jit);
+static void InterpreterFallback(u32 pc, Dynarmic::Jit* jit, void*);
 static Dynarmic::UserCallbacks GetUserCallbacks();
 
 static u32 MemoryRead32(u32 vaddr) {
@@ -26,7 +26,7 @@ static u32 MemoryRead32(u32 vaddr) {
     return vaddr;
 }
 
-static void InterpreterFallback(u32 pc, Dynarmic::Jit* jit) {
+static void InterpreterFallback(u32 pc, Dynarmic::Jit* jit, void*) {
     ARMul_State interp_state{USER32MODE};
     interp_state.user_callbacks = GetUserCallbacks();
     interp_state.NumInstrsToExecute = 1;