diff --git a/src/backend/x64/a64_emit_x64.cpp b/src/backend/x64/a64_emit_x64.cpp
index da37ab68..411ed281 100644
--- a/src/backend/x64/a64_emit_x64.cpp
+++ b/src/backend/x64/a64_emit_x64.cpp
@@ -204,18 +204,18 @@ void A64EmitX64::GenMemory128Accessors() {
 
 void A64EmitX64::GenFastmemFallbacks() {
     const std::initializer_list<int> idxes{0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15};
-    const std::vector<std::tuple<size_t, ArgCallback>> read_callbacks {
+    const std::array<std::pair<size_t, ArgCallback>, 4> read_callbacks{{
         {8, Devirtualize<&A64::UserCallbacks::MemoryRead8>(conf.callbacks)},
         {16, Devirtualize<&A64::UserCallbacks::MemoryRead16>(conf.callbacks)},
         {32, Devirtualize<&A64::UserCallbacks::MemoryRead32>(conf.callbacks)},
         {64, Devirtualize<&A64::UserCallbacks::MemoryRead64>(conf.callbacks)},
-    };
-    const std::vector<std::tuple<size_t, ArgCallback>> write_callbacks {
+    }};
+    const std::array<std::pair<size_t, ArgCallback>, 4> write_callbacks{{
         {8, Devirtualize<&A64::UserCallbacks::MemoryWrite8>(conf.callbacks)},
         {16, Devirtualize<&A64::UserCallbacks::MemoryWrite16>(conf.callbacks)},
         {32, Devirtualize<&A64::UserCallbacks::MemoryWrite32>(conf.callbacks)},
         {64, Devirtualize<&A64::UserCallbacks::MemoryWrite64>(conf.callbacks)},
-    };
+    }};
 
     for (int vaddr_idx : idxes) {
         if (vaddr_idx == 4 || vaddr_idx == 15) {
@@ -255,7 +255,7 @@ void A64EmitX64::GenFastmemFallbacks() {
                 continue;
             }
 
-            for (auto& [bitsize, callback] : read_callbacks) {
+            for (const auto& [bitsize, callback] : read_callbacks) {
                 code.align();
                 read_fallbacks[std::make_tuple(bitsize, vaddr_idx, value_idx)] = code.getCurr<void(*)()>();
                 ABI_PushCallerSaveRegistersAndAdjustStackExcept(code, HostLocRegIdx(value_idx));
@@ -271,7 +271,7 @@ void A64EmitX64::GenFastmemFallbacks() {
                 PerfMapRegister(read_fallbacks[std::make_tuple(bitsize, vaddr_idx, value_idx)], code.getCurr(), fmt::format("a64_read_fallback_{}", bitsize));
             }
 
-            for (auto& [bitsize, callback] : write_callbacks) {
+            for (const auto& [bitsize, callback] : write_callbacks) {
                 code.align();
                 write_fallbacks[std::make_tuple(bitsize, vaddr_idx, value_idx)] = code.getCurr<void(*)()>();
                 ABI_PushCallerSaveRegistersAndAdjustStack(code);