diff --git a/include/oaknut/impl/offset.hpp b/include/oaknut/impl/offset.hpp
index fb6ca87..a9634ac 100644
--- a/include/oaknut/impl/offset.hpp
+++ b/include/oaknut/impl/offset.hpp
@@ -78,7 +78,7 @@ struct PageOffset {
 
     static std::uint32_t encode(std::uintptr_t current_addr, std::uintptr_t target)
     {
-        std::uint64_t diff = (static_cast<std::uint64_t>(target) >> shift_amount) - (static_cast<std::uint64_t>(current_addr) >> shift_amount);
+        std::uint64_t diff = static_cast<std::uint64_t>((static_cast<std::int64_t>(target - current_addr) >> shift_amount));
         if (detail::sign_extend<bitsize>(diff) != diff)
             throw OaknutException{ExceptionType::OffsetOutOfRange};
         diff &= detail::mask_from_size(bitsize);
diff --git a/tests/basic.cpp b/tests/basic.cpp
index 7b401f6..32395c6 100644
--- a/tests/basic.cpp
+++ b/tests/basic.cpp
@@ -138,6 +138,11 @@ TEST_CASE("ADR")
     }
 }
 
+TEST_CASE("PageOffset")
+{
+    REQUIRE(PageOffset<21, 12>::encode(0x0000000088e74000, 0xffffffffd167dece) == 0xd2202);
+}
+
 TEST_CASE("ADRP")
 {
     CodeBlock mem{4096};