diff --git a/src/cpu/arm/half_signed_data_transfer.zig b/src/cpu/arm/half_signed_data_transfer.zig
index ae9b1cb..b479656 100644
--- a/src/cpu/arm/half_signed_data_transfer.zig
+++ b/src/cpu/arm/half_signed_data_transfer.zig
@@ -15,7 +15,7 @@ pub fn halfAndSignedDataTransfer(comptime P: bool, comptime U: bool, comptime I:
             const rm = opcode & 0xF;
             const imm_offset_high = opcode >> 8 & 0xF;
 
-            const base = cpu.r[rn] + if (!L) 4 else @as(u32, 0);
+            const base = cpu.r[rn] + if (!L and rn == 0xF) 4 else @as(u32, 0);
             const offset = if (I) imm_offset_high << 4 | rm else cpu.r[rm];
 
             const modified_base = if (U) base +% offset else base -% offset;