diff --git a/target/s390x/insn-data.def b/target/s390x/insn-data.def
index cac0f51ac6..3c3541cfbf 100644
--- a/target/s390x/insn-data.def
+++ b/target/s390x/insn-data.def
@@ -327,9 +327,9 @@
     C(0xeb57, XIY,     SIY,   LD,  m1_8u, i2_8u, new, m1_8, xor, nz64)
 
 /* EXECUTE */
-    C(0x4400, EX,      RX_a,  Z,   r1_o, a2, 0, 0, ex, 0)
+    C(0x4400, EX,      RX_a,  Z,   0, a2, 0, 0, ex, 0)
 /* EXECUTE RELATIVE LONG */
-    C(0xc600, EXRL,    RIL_b, EE,  r1_o, ri2, 0, 0, ex, 0)
+    C(0xc600, EXRL,    RIL_b, EE,  0, ri2, 0, 0, ex, 0)
 
 /* EXTRACT ACCESS */
     C(0xb24f, EAR,     RRE,   Z,   0, 0, new, r1_32, ear, 0)
diff --git a/target/s390x/translate.c b/target/s390x/translate.c
index c1162a134d..78c14ef6ce 100644
--- a/target/s390x/translate.c
+++ b/target/s390x/translate.c
@@ -2164,15 +2164,27 @@ static ExitStatus op_ex(DisasContext *s, DisasOps *o)
        MVC inside of memcpy, which needs a helper call anyway.  So
        perhaps this doesn't bear thinking about any further.  */
 
+    int r1 = get_field(s->fields, r1);
     TCGv_i32 ilen;
+    TCGv_i64 v1;
 
     update_psw_addr(s);
     gen_op_calc_cc(s);
 
+    if (r1 == 0) {
+        v1 = tcg_const_i64(0);
+    } else {
+        v1 = regs[r1];
+    }
+
     ilen = tcg_const_i32(s->next_pc - s->pc);
-    gen_helper_ex(cpu_env, ilen, o->in1, o->in2);
+    gen_helper_ex(cpu_env, ilen, v1, o->in2);
     tcg_temp_free_i32(ilen);
 
+    if (r1 == 0) {
+        tcg_temp_free_i64(v1);
+    }
+
     return NO_EXIT;
 }