diff --git a/ThunkLibs/include/common/Host.h b/ThunkLibs/include/common/Host.h
index 3783dab569..d69cfd9f48 100644
--- a/ThunkLibs/include/common/Host.h
+++ b/ThunkLibs/include/common/Host.h
@@ -227,6 +227,13 @@ const host_layout<T>& to_host_layout(const T& t) {
   return reinterpret_cast<const host_layout<T>&>(t);
 }
 
+template<typename T>
+constexpr bool is_long_or_longlong =
+    std::is_same_v<T, long> ||
+    std::is_same_v<T, unsigned long> ||
+    std::is_same_v<T, long long> ||
+    std::is_same_v<T, unsigned long long>;
+
 template<typename T>
 struct host_layout<T*> {
   T* data;
@@ -243,10 +250,12 @@ struct host_layout<T*> {
   // This is useful for handling "long"/"long long" on 64-bit, which are distinct types
   // but have equal data layout.
   template<typename U>
-  explicit host_layout(const guest_layout<U*>& from) requires (std::is_integral_v<T> && std::is_integral_v<U> && sizeof(T) == sizeof(U) && std::is_same_v<std::make_signed_t<std::remove_cv_t<T>>, long> && std::is_convertible_v<T, U> && std::is_signed_v<T> == std::is_signed_v<U>) : data { (T*)(uintptr_t)from.data } {
-  }
-  template<typename U>
-  explicit host_layout(const guest_layout<U*>& from) requires (std::is_integral_v<T> && std::is_integral_v<U> && sizeof(T) == sizeof(U) && std::is_same_v<std::make_signed_t<std::remove_cv_t<T>>, long long> && std::is_convertible_v<T, U> && std::is_signed_v<T> == std::is_signed_v<U>) : data { (T*)(uintptr_t)from.data } {
+  explicit host_layout(const guest_layout<U*>& from) requires (is_long_or_longlong<std::remove_cv_t<T>> && std::is_integral_v<U> && std::is_convertible_v<T, U> && std::is_signed_v<T> == std::is_signed_v<U>
+#if __clang_major__ >= 16
+    // Old clang versions don't support using sizeof on incomplete types when evaluating requires()
+    && sizeof(T) == sizeof(U)
+#endif
+  ) : data { (T*)(uintptr_t)from.data } {
   }
 
   // Allow conversion of pointers to 8-bit integer types to "char*".
diff --git a/unittests/ThunkLibs/generator.cpp b/unittests/ThunkLibs/generator.cpp
index d32bf53ff4..b2f6411085 100644
--- a/unittests/ThunkLibs/generator.cpp
+++ b/unittests/ThunkLibs/generator.cpp
@@ -305,12 +305,14 @@ SourceWithAST Fixture::run_thunkgen_host(std::string_view prelude, std::string_v
         "  template<typename U> explicit host_layout(const guest_layout<U>&) requires (std::is_integral_v<U> && sizeof(U) <= sizeof(T) && std::is_convertible_v<T, U> && std::is_signed_v<T> == std::is_signed_v<U>);\n"
         "};\n"
         "\n"
+        "template<typename T> constexpr bool is_long = std::is_same_v<T, long> || std::is_same_v<T, unsigned long>;\n"
+        "template<typename T> constexpr bool is_longlong = std::is_same_v<T, long long> || std::is_same_v<T, unsigned long long>;\n"
         "template<typename T>\n"
         "struct host_layout<T*> {\n"
         "  T* data;\n"
         "  explicit host_layout(const guest_layout<T*>&);\n"
-        "  template<typename U> explicit host_layout(const guest_layout<U*>&) requires (std::is_integral_v<T> && std::is_integral_v<U> && sizeof(T) == sizeof(U) && std::is_same_v<std::make_signed_t<std::remove_cv_t<T>>, long> && std::is_convertible_v<T, U> && std::is_signed_v<T> == std::is_signed_v<U>);\n"
-        "  template<typename U> explicit host_layout(const guest_layout<U*>&) requires (std::is_integral_v<T> && std::is_integral_v<U> && sizeof(T) == sizeof(U) && std::is_same_v<std::make_signed_t<std::remove_cv_t<T>>, long long> && std::is_convertible_v<T, U> && std::is_signed_v<T> == std::is_signed_v<U>);\n"
+        "  template<typename U> explicit host_layout(const guest_layout<U*>&) requires (std::is_integral_v<U> && sizeof(U) == sizeof(long) && sizeof(long) == 8 && is_long<std::remove_cv_t<T>> && std::is_convertible_v<T, U> && std::is_signed_v<T> == std::is_signed_v<U>);\n"
+        "  template<typename U> explicit host_layout(const guest_layout<U*>&) requires (std::is_integral_v<U> && sizeof(U) == sizeof(long long) && is_longlong<std::remove_cv_t<T>> && std::is_convertible_v<T, U> && std::is_signed_v<T> == std::is_signed_v<U>);\n"
         "  template<typename U> explicit host_layout(const guest_layout<U*>&) requires (std::is_same_v<std::remove_cv_t<T>, char> && std::is_integral_v<U> && std::is_convertible_v<T, U> && sizeof(U) == 1);\n"
         "  template<typename U> explicit host_layout(const guest_layout<U*>&) requires (std::is_same_v<std::remove_cv_t<T>, wchar_t> && std::is_integral_v<U> && std::is_convertible_v<T, U> && sizeof(U) == sizeof(wchar_t));\n"
         "};\n"