diff --git a/sdbuild/boot/meta-pynq/recipes-apps/pynq-cpp/files/cpp/mmio.cc b/sdbuild/boot/meta-pynq/recipes-apps/pynq-cpp/files/cpp/mmio.cc
index 17d99248c..59312505b 100644
--- a/sdbuild/boot/meta-pynq/recipes-apps/pynq-cpp/files/cpp/mmio.cc
+++ b/sdbuild/boot/meta-pynq/recipes-apps/pynq-cpp/files/cpp/mmio.cc
@@ -5,9 +5,9 @@
 MMIO::MMIO(off_t base_address, size_t length_p)
     : mem_fd(-1), virt_base(0), virt_offset(0), length(0), mapped_base(nullptr)
 {
-    if (base_address < 0 || length_p < 0)
+    if (length_p < 0)
     {
-        std::cerr << "Error: Base address or length cannot be negative." << std::endl;
+        std::cerr << "Error: Length cannot be negative." << std::endl;
         return;
     }
     mem_fd = open("/dev/mem", O_RDWR | O_SYNC);
@@ -17,7 +17,7 @@ MMIO::MMIO(off_t base_address, size_t length_p)
         return;
     }
     virt_base = base_address & ~(4096 - 1);
-    virt_offset = base_address - virt_base;
+    virt_offset = base_address & (4096 - 1);
     length = length_p;
 
     mapped_base = mmap(nullptr, length + virt_offset, PROT_READ | PROT_WRITE, MAP_SHARED, mem_fd, virt_base);
@@ -70,4 +70,4 @@ void MMIO::write(uint32_t data, uint64_t offset)
     std::cout << "MMIO Write to " << static_cast<void *>(mapped_base) << " Data: " << data << " Offset: " << offset << std::endl;
 #endif
     ptr[idx] = data;
-}
\ No newline at end of file
+}