diff --git a/target/m68k/cpu.c b/target/m68k/cpu.c
index ff3c4c1c98..37d2ed9dc7 100644
--- a/target/m68k/cpu.c
+++ b/target/m68k/cpu.c
@@ -160,6 +160,7 @@ static void m68020_cpu_initfn(Object *obj)
     m68k_set_feature(env, M68K_FEATURE_FPU);
     m68k_set_feature(env, M68K_FEATURE_CAS);
     m68k_set_feature(env, M68K_FEATURE_CHK2);
+    m68k_set_feature(env, M68K_FEATURE_MSP);
 }
 
 /*
diff --git a/target/m68k/cpu.h b/target/m68k/cpu.h
index 5d2cb012e5..7c3feeaf8a 100644
--- a/target/m68k/cpu.h
+++ b/target/m68k/cpu.h
@@ -85,7 +85,13 @@ typedef struct CPUM68KState {
     uint32_t pc;
     uint32_t sr;
 
-    /* SSP and USP.  The current_sp is stored in aregs[7], the other here.  */
+    /*
+     * The 68020/30/40 support two supervisor stacks, ISP and MSP.
+     * The 68000/10, Coldfire, and CPU32 only have USP/SSP.
+     *
+     * The current_sp is stored in aregs[7], the other here.
+     * The USP, SSP, and if used the additional ISP for 68020/30/40.
+     */
     int current_sp;
     uint32_t sp[3];
 
@@ -484,6 +490,7 @@ enum m68k_features {
     M68K_FEATURE_CF_EMAC,
     M68K_FEATURE_CF_EMAC_B,   /* Revision B EMAC (dual accumulate). */
     M68K_FEATURE_USP, /* User Stack Pointer. (680[012346]0, ISA A+, B or C).*/
+    M68K_FEATURE_MSP, /* Master Stack Pointer. (680[234]0) */
     M68K_FEATURE_EXT_FULL,    /* 68020+ full extension word. */
     M68K_FEATURE_WORD_INDEX,  /* word sized address index registers. */
     M68K_FEATURE_SCALED_INDEX, /* scaled address index registers. */
diff --git a/target/m68k/helper.c b/target/m68k/helper.c
index 1efd6e4f65..4185ca94ce 100644
--- a/target/m68k/helper.c
+++ b/target/m68k/helper.c
@@ -463,7 +463,8 @@ void m68k_switch_sp(CPUM68KState *env)
     env->sp[env->current_sp] = env->aregs[7];
     if (m68k_feature(env, M68K_FEATURE_M68000)) {
         if (env->sr & SR_S) {
-            if (env->sr & SR_M) {
+            /* SR:Master-Mode bit unimplemented then ISP is not available */
+            if (!m68k_feature(env, M68K_FEATURE_MSP) || env->sr & SR_M) {
                 new_sp = M68K_SSP;
             } else {
                 new_sp = M68K_ISP;