diff --git a/src/arm/cpu/arm/block_data_transfer.zig b/src/arm/cpu/arm/block_data_transfer.zig
index c1d3283..6c9a8f1 100644
--- a/src/arm/cpu/arm/block_data_transfer.zig
+++ b/src/arm/cpu/arm/block_data_transfer.zig
@@ -38,7 +38,7 @@ pub fn blockDataTransfer(comptime InstrFn: type, comptime P: bool, comptime U: b
                     const undefined_addr: u32 = if (U) blk: {
                         break :blk cpu.r[rn] + if (P) 4 else 0;
                     } else blk: {
-                        break :blk cpu.r[rn] - 0x40 - if (!P) 4 else 0;
+                        break :blk cpu.r[rn] - (0x40 - if (!P) 4 else 0);
                     };
 
                     if (L) {