diff --git a/linux-user/nios2/cpu_loop.c b/linux-user/nios2/cpu_loop.c
index a5e86990e2..da77ede76b 100644
--- a/linux-user/nios2/cpu_loop.c
+++ b/linux-user/nios2/cpu_loop.c
@@ -50,6 +50,18 @@ void cpu_loop(CPUNios2State *env)
                             env->ctrl[CR_BADADDR]);
             break;
 
+        case EXCP_ILLEGAL:
+        case EXCP_UNIMPL:
+            /* Match kernel's handle_illegal_c(). */
+            env->pc -= 4;
+            force_sig_fault(TARGET_SIGILL, TARGET_ILL_ILLOPC, env->pc);
+            break;
+        case EXCP_SUPERI:
+            /* Match kernel's handle_supervisor_instr(). */
+            env->pc -= 4;
+            force_sig_fault(TARGET_SIGILL, TARGET_ILL_PRVOPC, env->pc);
+            break;
+
         case EXCP_TRAP:
             switch (env->error_code) {
             case 0: