diff --git a/src/isa-thumb.c b/src/isa-thumb.c
index 7c2583817..05b68e550 100644
--- a/src/isa-thumb.c
+++ b/src/isa-thumb.c
@@ -245,8 +245,8 @@ DEFINE_CONDITIONAL_BRANCH_THUMB(LT)
 DEFINE_CONDITIONAL_BRANCH_THUMB(GT)
 DEFINE_CONDITIONAL_BRANCH_THUMB(LE)
 
-DEFINE_INSTRUCTION_THUMB(ADD7, ARM_STUB)
-DEFINE_INSTRUCTION_THUMB(SUB4, ARM_STUB)
+DEFINE_INSTRUCTION_THUMB(ADD7, cpu->gprs[ARM_SP] += (opcode & 0x7F) << 2)
+DEFINE_INSTRUCTION_THUMB(SUB4, cpu->gprs[ARM_SP] -= (opcode & 0x7F) << 2)
 
 DEFINE_LOAD_STORE_MULTIPLE_EX_THUMB(POP, \
 	opcode & 0x00FF, \