diff --git a/target-arm/cpu.c b/target-arm/cpu.c
index 45ad7f0..8294342 100644
--- a/target-arm/cpu.c
+++ b/target-arm/cpu.c
@@ -128,7 +128,7 @@ static void arm_cpu_reset(CPUState *s)
         }
     }
 
-    if (env->cp15.c1_sys & (1 << 13)) {
+    if (env->cp15.c1_sys & SCTLR_V) {
             env->regs[15] = 0xFFFF0000;
     }
 
diff --git a/target-arm/cpu.h b/target-arm/cpu.h
index 383c582..52894fc 100644
--- a/target-arm/cpu.h
+++ b/target-arm/cpu.h
@@ -337,6 +337,58 @@ int cpu_arm_handle_mmu_fault (CPUARMState *env, target_ulong address, int rw,
                               int mmu_idx);
 #define cpu_handle_mmu_fault cpu_arm_handle_mmu_fault
 
+/* SCTLR bit meanings. Several bits have been reused in newer
+ * versions of the architecture; in that case we define constants
+ * for both old and new bit meanings. Code which tests against those
+ * bits should probably check or otherwise arrange that the CPU
+ * is the architectural version it expects.
+ */
+#define SCTLR_M       (1U << 0)
+#define SCTLR_A       (1U << 1)
+#define SCTLR_C       (1U << 2)
+#define SCTLR_W       (1U << 3) /* up to v6; RAO in v7 */
+#define SCTLR_SA      (1U << 3)
+#define SCTLR_P       (1U << 4) /* up to v5; RAO in v6 and v7 */
+#define SCTLR_SA0     (1U << 4) /* v8 onward, AArch64 only */
+#define SCTLR_D       (1U << 5) /* up to v5; RAO in v6 */
+#define SCTLR_CP15BEN (1U << 5) /* v7 onward */
+#define SCTLR_L       (1U << 6) /* up to v5; RAO in v6 and v7; RAZ in v8 */
+#define SCTLR_B       (1U << 7) /* up to v6; RAZ in v7 */
+#define SCTLR_ITD     (1U << 7) /* v8 onward */
+#define SCTLR_S       (1U << 8) /* up to v6; RAZ in v7 */
+#define SCTLR_SED     (1U << 8) /* v8 onward */
+#define SCTLR_R       (1U << 9) /* up to v6; RAZ in v7 */
+#define SCTLR_UMA     (1U << 9) /* v8 onward, AArch64 only */
+#define SCTLR_F       (1U << 10) /* up to v6 */
+#define SCTLR_SW      (1U << 10) /* v7 onward */
+#define SCTLR_Z       (1U << 11)
+#define SCTLR_I       (1U << 12)
+#define SCTLR_V       (1U << 13)
+#define SCTLR_RR      (1U << 14) /* up to v7 */
+#define SCTLR_DZE     (1U << 14) /* v8 onward, AArch64 only */
+#define SCTLR_L4      (1U << 15) /* up to v6; RAZ in v7 */
+#define SCTLR_UCT     (1U << 15) /* v8 onward, AArch64 only */
+#define SCTLR_DT      (1U << 16) /* up to ??, RAO in v6 and v7 */
+#define SCTLR_nTWI    (1U << 16) /* v8 onward */
+#define SCTLR_HA      (1U << 17)
+#define SCTLR_IT      (1U << 18) /* up to ??, RAO in v6 and v7 */
+#define SCTLR_nTWE    (1U << 18) /* v8 onward */
+#define SCTLR_WXN     (1U << 19)
+#define SCTLR_ST      (1U << 20) /* up to ??, RAZ in v6 */
+#define SCTLR_UWXN    (1U << 20) /* v7 onward */
+#define SCTLR_FI      (1U << 21)
+#define SCTLR_U       (1U << 22)
+#define SCTLR_XP      (1U << 23) /* up to v6; v7 onward RAO */
+#define SCTLR_VE      (1U << 24) /* up to v7 */
+#define SCTLR_E0E     (1U << 24) /* v8 onward, AArch64 only */
+#define SCTLR_EE      (1U << 25)
+#define SCTLR_L2      (1U << 26) /* up to v6, RAZ in v7 */
+#define SCTLR_UCI     (1U << 26) /* v8 onward, AArch64 only */
+#define SCTLR_NMFI    (1U << 27)
+#define SCTLR_TRE     (1U << 28)
+#define SCTLR_AFE     (1U << 29)
+#define SCTLR_TE      (1U << 30)
+
 #define CPSR_M (0x1fU)
 #define CPSR_T (1U << 5)
 #define CPSR_F (1U << 6)
diff --git a/target-arm/helper.c b/target-arm/helper.c
index 5ae08c9..d9e94f2 100644
--- a/target-arm/helper.c
+++ b/target-arm/helper.c
@@ -2718,7 +2718,7 @@ void arm_cpu_do_interrupt(CPUState *cs)
         return; /* Never happens.  Keep compiler happy.  */
     }
     /* High vectors.  */
-    if (env->cp15.c1_sys & (1 << 13)) {
+    if (env->cp15.c1_sys & SCTLR_V) {
         /* when enabled, base address cannot be remapped.  */
         addr += 0xffff0000;
     } else {
@@ -2741,7 +2741,7 @@ void arm_cpu_do_interrupt(CPUState *cs)
     /* this is a lie, as the was no c1_sys on V4T/V5, but who cares
      * and we should just guard the thumb mode on V4 */
     if (arm_feature(env, ARM_FEATURE_V4T)) {
-        env->thumb = (env->cp15.c1_sys & (1 << 30)) != 0;
+        env->thumb = (env->cp15.c1_sys & SCTLR_TE) != 0;
     }
     env->regs[14] = env->regs[15] + offset;
     env->regs[15] = addr;
@@ -2769,10 +2769,10 @@ static inline int check_ap(CPUARMState *env, int ap, int domain_prot,
   case 0:
       if (access_type == 1)
           return 0;
-      switch ((env->cp15.c1_sys >> 8) & 3) {
-      case 1:
+      switch (env->cp15.c1_sys & (SCTLR_S | SCTLR_R)) {
+      case SCTLR_S:
           return is_user ? 0 : PAGE_READ;
-      case 2:
+      case SCTLR_R:
           return PAGE_READ;
       default:
           return 0;
@@ -3003,7 +3003,7 @@ static int get_phys_addr_v6(CPUARMState *env, uint32_t address, int access_type,
             goto do_fault;
 
         /* The simplified model uses AP[0] as an access control bit.  */
-        if ((env->cp15.c1_sys & (1 << 29)) && (ap & 1) == 0) {
+        if ((env->cp15.c1_sys & SCTLR_AFE) && (ap & 1) == 0) {
             /* Access flag fault.  */
             code = (code == 15) ? 6 : 3;
             goto do_fault;
@@ -3295,7 +3295,7 @@ static inline int get_phys_addr(CPUARMState *env, uint32_t address,
     if (address < 0x02000000)
         address += env->cp15.c13_fcse;
 
-    if ((env->cp15.c1_sys & 1) == 0) {
+    if ((env->cp15.c1_sys & SCTLR_M) == 0) {
         /* MMU/MPU disabled.  */
         *phys_ptr = address;
         *prot = PAGE_READ | PAGE_WRITE | PAGE_EXEC;
@@ -3308,7 +3308,7 @@ static inline int get_phys_addr(CPUARMState *env, uint32_t address,
     } else if (extended_addresses_enabled(env)) {
         return get_phys_addr_lpae(env, address, access_type, is_user, phys_ptr,
                                   prot, page_size);
-    } else if (env->cp15.c1_sys & (1 << 23)) {
+    } else if (env->cp15.c1_sys & SCTLR_XP) {
         return get_phys_addr_v6(env, address, access_type, is_user, phys_ptr,
                                 prot, page_size);
     } else {
