diff --git a/target/s390x/tcg/mem_helper.c b/target/s390x/tcg/mem_helper.c
index 00afae2b64..96b8ef61b5 100644
--- a/target/s390x/tcg/mem_helper.c
+++ b/target/s390x/tcg/mem_helper.c
@@ -2468,8 +2468,16 @@ void HELPER(stpq_parallel)(CPUS390XState *env, uint64_t addr,
 */
 void HELPER(ex)(CPUS390XState *env, uint32_t ilen, uint64_t r1, uint64_t addr)
 {
-    uint64_t insn = cpu_lduw_code(env, addr);
-    uint8_t opc = insn >> 8;
+    uint64_t insn;
+    uint8_t opc;
+
+    /* EXECUTE targets must be at even addresses.  */
+    if (addr & 1) {
+        tcg_s390_program_interrupt(env, PGM_SPECIFICATION, GETPC());
+    }
+
+    insn = cpu_lduw_code(env, addr);
+    opc = insn >> 8;
 
     /* Or in the contents of R1[56:63].  */
     insn |= r1 & 0xff;