diff --git a/src/isa-thumb.c b/src/isa-thumb.c
index 5b29a9b97..084cf501e 100644
--- a/src/isa-thumb.c
+++ b/src/isa-thumb.c
@@ -170,6 +170,7 @@ DEFINE_INSTRUCTION_WITH_HIGH_THUMB(MOV3, cpu->gprs[rd] = cpu->gprs[rm])
 #define DEFINE_IMMEDIATE_WITH_REGISTER_EX_THUMB(NAME, RD, BODY) \
 	DEFINE_INSTRUCTION_THUMB(NAME, \
 		int rd = RD; \
+		int immediate = (opcode & 0x00FF) << 2; \
 		BODY;)
 
 #define DEFINE_IMMEDIATE_WITH_REGISTER_THUMB(NAME, BODY) \
@@ -180,7 +181,7 @@ DEFINE_IMMEDIATE_WITH_REGISTER_THUMB(LDR4, ARM_STUB)
 DEFINE_IMMEDIATE_WITH_REGISTER_THUMB(STR3, ARM_STUB)
 
 DEFINE_IMMEDIATE_WITH_REGISTER_THUMB(ADD5, ARM_STUB)
-DEFINE_IMMEDIATE_WITH_REGISTER_THUMB(ADD6, ARM_STUB)
+DEFINE_IMMEDIATE_WITH_REGISTER_THUMB(ADD6, cpu->gprs[rd] = cpu->gprs[ARM_SP] + immediate)
 
 #define DEFINE_LOAD_STORE_WITH_REGISTER_EX_THUMB(NAME, RM, BODY) \
 	DEFINE_INSTRUCTION_THUMB(NAME, \