diff --git a/src/arm/arm.h b/src/arm/arm.h
index 8ec290613..e4eeeddaf 100644
--- a/src/arm/arm.h
+++ b/src/arm/arm.h
@@ -54,13 +54,13 @@ union PSR {
 	struct {
 		enum PrivilegeMode priv : 5;
 		enum ExecutionMode t : 1;
-		int f : 1;
-		int i : 1;
-		int : 20;
-		int v : 1;
-		int c : 1;
-		int z : 1;
-		int n : 1;
+		unsigned f : 1;
+		unsigned i : 1;
+		unsigned : 20;
+		unsigned v : 1;
+		unsigned c : 1;
+		unsigned z : 1;
+		unsigned n : 1;
 	};
 
 	int32_t packed;
diff --git a/src/arm/isa-thumb.c b/src/arm/isa-thumb.c
index 0e980ce27..37372a13f 100644
--- a/src/arm/isa-thumb.c
+++ b/src/arm/isa-thumb.c
@@ -247,8 +247,17 @@ DEFINE_DATA_FORM_5_INSTRUCTION_THUMB(ASR2,
 	}
 	THUMB_NEUTRAL_S( , , cpu->gprs[rd]))
 
-DEFINE_DATA_FORM_5_INSTRUCTION_THUMB(ADC, ARM_STUB)
-DEFINE_DATA_FORM_5_INSTRUCTION_THUMB(SBC, ARM_STUB)
+DEFINE_DATA_FORM_5_INSTRUCTION_THUMB(ADC,
+	int n = cpu->gprs[rn] + cpu->cpsr.c;
+	int d = cpu->gprs[rd];
+	cpu->gprs[rd] = d + n;
+	THUMB_ADDITION_S(d, n, cpu->gprs[rd]);)
+
+DEFINE_DATA_FORM_5_INSTRUCTION_THUMB(SBC,
+	int n = cpu->gprs[rn] + !cpu->cpsr.c;
+	int d = cpu->gprs[rd];
+	cpu->gprs[rd] = d - n;
+	THUMB_SUBTRACTION_S(d, n, cpu->gprs[rd]);)
 DEFINE_DATA_FORM_5_INSTRUCTION_THUMB(ROR,
 	int rs = cpu->gprs[rn] & 0xFF;
 	if (rs) {