diff --git a/linux-user/arm/cpu_loop.c b/linux-user/arm/cpu_loop.c
index 3268e5f1f1..d950409d5b 100644
--- a/linux-user/arm/cpu_loop.c
+++ b/linux-user/arm/cpu_loop.c
@@ -230,7 +230,7 @@ do_kernel_trap(CPUARMState *env)
     /* Jump back to the caller.  */
     addr = env->regs[14];
     if (addr & 1) {
-        env->thumb = 1;
+        env->thumb = true;
         addr &= ~1;
     }
     env->regs[15] = addr;
diff --git a/target/arm/cpu.c b/target/arm/cpu.c
index 7e9f7d146d..e3f8215203 100644
--- a/target/arm/cpu.c
+++ b/target/arm/cpu.c
@@ -51,7 +51,7 @@ static void arm_cpu_set_pc(CPUState *cs, vaddr value)
 
     if (is_a64(env)) {
         env->pc = value;
-        env->thumb = 0;
+        env->thumb = false;
     } else {
         env->regs[15] = value & ~1;
         env->thumb = value & 1;
diff --git a/target/arm/cpu.h b/target/arm/cpu.h
index 31e4670927..d2a34f6ea8 100644
--- a/target/arm/cpu.h
+++ b/target/arm/cpu.h
@@ -260,6 +260,7 @@ typedef struct CPUArchState {
      */
     uint32_t pstate;
     bool aarch64; /* True if CPU is in aarch64 state; inverse of PSTATE.nRW */
+    bool thumb;   /* True if CPU is in thumb mode; cpsr[5] */
 
     /* Cached TBFLAGS state.  See below for which bits are included.  */
     CPUARMTBFlags hflags;
@@ -286,7 +287,6 @@ typedef struct CPUArchState {
     uint32_t ZF; /* Z set if zero.  */
     uint32_t QF; /* 0 or 1 */
     uint32_t GE; /* cpsr[19:16] */
-    uint32_t thumb; /* cpsr[5]. 0 = arm mode, 1 = thumb mode. */
     uint32_t condexec_bits; /* IT bits.  cpsr[15:10,26:25].  */
     uint32_t btype;  /* BTI branch type.  spsr[11:10].  */
     uint64_t daif; /* exception masks, in the bits they are in PSTATE */
diff --git a/target/arm/m_helper.c b/target/arm/m_helper.c
index b7a0fe0114..a740c3e160 100644
--- a/target/arm/m_helper.c
+++ b/target/arm/m_helper.c
@@ -564,7 +564,7 @@ void HELPER(v7m_bxns)(CPUARMState *env, uint32_t dest)
         env->v7m.control[M_REG_S] &= ~R_V7M_CONTROL_SFPA_MASK;
     }
     switch_v7m_security_state(env, dest & 1);
-    env->thumb = 1;
+    env->thumb = true;
     env->regs[15] = dest & ~1;
     arm_rebuild_hflags(env);
 }
@@ -590,7 +590,7 @@ void HELPER(v7m_blxns)(CPUARMState *env, uint32_t dest)
          * except that the low bit doesn't indicate Thumb/not.
          */
         env->regs[14] = nextinst;
-        env->thumb = 1;
+        env->thumb = true;
         env->regs[15] = dest & ~1;
         return;
     }
@@ -626,7 +626,7 @@ void HELPER(v7m_blxns)(CPUARMState *env, uint32_t dest)
     }
     env->v7m.control[M_REG_S] &= ~R_V7M_CONTROL_SFPA_MASK;
     switch_v7m_security_state(env, 0);
-    env->thumb = 1;
+    env->thumb = true;
     env->regs[15] = dest;
     arm_rebuild_hflags(env);
 }