diff --git a/devices/video/atimach64defs.h b/devices/video/atimach64defs.h
index 475b9c38fb..be1ccd6568 100644
--- a/devices/video/atimach64defs.h
+++ b/devices/video/atimach64defs.h
@@ -692,6 +692,10 @@ constexpr auto MM_REGS_0_OFF = 0x007FFC00U; // offset to memory mapped registers
 constexpr auto MM_REGS_1_OFF = 0x007FF800U; // offset to memory mapped registers, block 1
 constexpr auto MM_REGS_2_OFF = 0x003FFC00U; // offset to memory mapped registers, 4MB aperture
 
+// Auxiliary register aperture.
+constexpr auto MM_STDL_REGS_0_OFF = 0x400U; // offset to memory mapped registers, block 0
+constexpr auto MM_STDL_REGS_1_OFF = 0x000U; // offset to memory mapped registers, block 1
+
 constexpr auto ATI_XTAL = 14318180.0f; // external crystal oscillator frequency
 
 #endif // ATI_MACH64_DEFS_H
diff --git a/devices/video/atirage.cpp b/devices/video/atirage.cpp
index 0d29fe82e7..8f9ef2551a 100644
--- a/devices/video/atirage.cpp
+++ b/devices/video/atirage.cpp
@@ -627,9 +627,16 @@ uint32_t ATIRage::read(uint32_t rgn_start, uint32_t offset, int size)
     }
 
     if (rgn_start == this->aperture_base[2] && offset < this->aperture_size[2]) {
-        LOG_F(WARNING, "%s: read  unmapped aperture[2] region %08x.%c",
-              this->name.c_str(), offset, SIZE_ARG(size));
-        return 0;
+        // The documentation for the Rage LT Pro marks the upper 2KB
+        // of the 4KB aux. aperture reserved, but it's used by Mac OS
+        // anyway for Rage II. Make it wrap around the 2KB boundary
+        // instead.
+        offset &= 0x7ff;
+        if (offset >= MM_STDL_REGS_0_OFF) {
+            return BYTESWAP_SIZED(this->read_reg(offset & 0x3FF, size), size);
+        }
+        // Rest of the region is Block 1.
+        return BYTESWAP_SIZED(this->read_reg((offset & 0x3FF) + 0x400, size), size);
     }
 
     // memory mapped expansion ROM region
@@ -674,9 +681,12 @@ void ATIRage::write(uint32_t rgn_start, uint32_t offset, uint32_t value, int siz
     }
 
     if (rgn_start == this->aperture_base[2] && offset < this->aperture_size[2]) {
-        LOG_F(WARNING, "%s: write unmapped aperture[2] region %08x.%c = %0*x",
-              this->name.c_str(), offset, SIZE_ARG(size), size * 2, value);
-        return;
+        // See the note about wrap around above.
+        offset &= 0x7ff;
+        if (offset >= MM_STDL_REGS_0_OFF) {
+            return this->write_reg(offset & 0x3FF, BYTESWAP_SIZED(value, size), size);
+        }
+        return this->write_reg((offset & 0x3FF) + 0x400, BYTESWAP_SIZED(value, size), size);
     }
 
     LOG_F(WARNING, "%s: write unmapped aperture region %08x.%c = %0*x",