diff --git a/src/cpu/arm/single_data_swap.zig b/src/cpu/arm/single_data_swap.zig
index c7b531a..f8e76cc 100644
--- a/src/cpu/arm/single_data_swap.zig
+++ b/src/cpu/arm/single_data_swap.zig
@@ -20,8 +20,8 @@ pub fn singleDataSwap(comptime B: bool) InstrFn {
                 cpu.r[rd] = value;
             } else {
                 // SWP
-                const value = std.math.rotr(u32, bus.read32(address), 8 * (address & 0x3));
-                bus.write32(address, cpu.r[rm]);
+                const value = std.math.rotr(u32, bus.read32(address & 0xFFFF_FFFC), 8 * (address & 0x3));
+                bus.write32(address & 0xFFFF_FFFC, cpu.r[rm]);
                 cpu.r[rd] = value;
             }
         }