diff --git a/src/isa-thumb.c b/src/isa-thumb.c
index 5af2134b9..5caa55dbe 100644
--- a/src/isa-thumb.c
+++ b/src/isa-thumb.c
@@ -223,7 +223,7 @@ DEFINE_DATA_FORM_5_INSTRUCTION_THUMB(ADC, ARM_STUB)
 DEFINE_DATA_FORM_5_INSTRUCTION_THUMB(SBC, ARM_STUB)
 DEFINE_DATA_FORM_5_INSTRUCTION_THUMB(ROR, ARM_STUB)
 DEFINE_DATA_FORM_5_INSTRUCTION_THUMB(TST, ARM_STUB)
-DEFINE_DATA_FORM_5_INSTRUCTION_THUMB(NEG, ARM_STUB)
+DEFINE_DATA_FORM_5_INSTRUCTION_THUMB(NEG, THUMB_SUBTRACTION(cpu->gprs[rd], 0, cpu->gprs[rn]))
 DEFINE_DATA_FORM_5_INSTRUCTION_THUMB(CMP2, ARM_STUB)
 DEFINE_DATA_FORM_5_INSTRUCTION_THUMB(CMN, ARM_STUB)
 DEFINE_DATA_FORM_5_INSTRUCTION_THUMB(ORR, cpu->gprs[rd] = cpu->gprs[rd] | cpu->gprs[rn]; THUMB_NEUTRAL_S( , , cpu->gprs[rd]))