diff --git a/src/hotspot/cpu/s390/assembler_s390.hpp b/src/hotspot/cpu/s390/assembler_s390.hpp
index 66243d6e0a9..9bb143001b9 100644
--- a/src/hotspot/cpu/s390/assembler_s390.hpp
+++ b/src/hotspot/cpu/s390/assembler_s390.hpp
@@ -140,7 +140,8 @@ class RelAddr {
     if ((target == nullptr) || (target == pc)) {
       return 0;  // Yet unknown branch destination.
     } else {
-      guarantee(is_in_range_of_RelAddr(target, pc, shortForm), "target not within reach");
+      guarantee(is_in_range_of_RelAddr(target, pc, shortForm),
+                "target not within reach at " INTPTR_FORMAT ", distance = " INTX_FORMAT, p2i(pc), (target - pc) );
       return (int)((target - pc)>>1);
     }
   }
diff --git a/src/hotspot/cpu/s390/c1_MacroAssembler_s390.cpp b/src/hotspot/cpu/s390/c1_MacroAssembler_s390.cpp
index 3a1f9c5e1fd..40edca6559a 100644
--- a/src/hotspot/cpu/s390/c1_MacroAssembler_s390.cpp
+++ b/src/hotspot/cpu/s390/c1_MacroAssembler_s390.cpp
@@ -101,7 +101,7 @@ void C1_MacroAssembler::lock_object(Register Rmark, Register Roop, Register Rbox
   if (DiagnoseSyncOnValueBasedClasses != 0) {
     load_klass(tmp, Roop);
     testbit(Address(tmp, Klass::access_flags_offset()), exact_log2(JVM_ACC_IS_VALUE_BASED_CLASS));
-    z_btrue(slow_case);
+    branch_optimized(Assembler::bcondAllOne, slow_case);
   }
 
   assert(LockingMode != LM_MONITOR, "LM_MONITOR is already handled, by emit_lock()");
@@ -170,7 +170,7 @@ void C1_MacroAssembler::unlock_object(Register Rmark, Register Roop, Register Rb
     z_lg(Rmark, Address(Roop, hdr_offset));
     z_lgr(tmp, Rmark);
     z_nill(tmp, markWord::monitor_value);
-    z_brnz(slow_case);
+    branch_optimized(Assembler::bcondNotZero, slow_case);
     lightweight_unlock(Roop, Rmark, tmp, slow_case);
   } else if (LockingMode == LM_LEGACY) {
     // Test if object header is pointing to the displaced header, and if so, restore