diff --git a/lib/perl5db.t b/lib/perl5db.t
index ab35f993e0dc..76e252c8777a 100644
--- a/lib/perl5db.t
+++ b/lib/perl5db.t
@@ -3662,6 +3662,35 @@ EOS
     $wrapper->contents_like(qr/print "2\\n"/, "break immediately after defining problem");
 }
 
+{
+    my $wrapper = DebugWrap->new(
+        {
+            cmds =>
+            [
+                "s",
+                "s",
+                "s",
+                "s",
+                "s",
+                "s",
+                "s",
+                "q",
+            ],
+            prog => \<<'EOS',
+use v5.40.0;
+sub four ($x1, $x2, $x3, $x4) { # start sub four
+    print $x1, $x2, $x3, $x4;
+}
+four(1,2,3,4);
+EOS
+        }
+       );
+    my $content = $wrapper->_contents;
+    my $count = () = $content =~ /start sub four/g;
+    is($count, 1, "expect to step on sub four entry once")
+      or diag $content;
+}
+
 done_testing();
 
 END {
diff --git a/op.c b/op.c
index d7fb28f035e6..76dee84167c6 100644
--- a/op.c
+++ b/op.c
@@ -8896,7 +8896,8 @@ Perl_newSTATEOP(pTHX_ I32 flags, char *label, OP *o)
     flags &= ~SVf_UTF8;
 
     NewOp(1101, cop, 1, COP);
-    if (PERLDB_LINE && CopLINE(PL_curcop) && PL_curstash != PL_debstash) {
+    if (PERLDB_LINE && CopLINE(PL_curcop) && PL_curstash != PL_debstash &&
+        !(flags & OPf_FORCE_NEXTSTATE)) {
         OpTYPE_set(cop, OP_DBSTATE);
     }
     else {
diff --git a/op.h b/op.h
index d64ef04db782..ef0cdd7796a7 100644
--- a/op.h
+++ b/op.h
@@ -171,6 +171,15 @@ Deprecated.  Use C<GIMME_V> instead.
    op_convert_list to set op_folded.  */
 #define OPf_FOLDED      (1<<16)
 
+/* In debugging mode newSTATEOP() normally makes an OP_DBSTATE, set
+   this to force creation of an OP_NEXTSTATE (which isn't
+   steppable/breakable) instead.
+
+   This is useful if you need to intro_my() but not make a breakable
+   op.
+ */
+#define OPf_FORCE_NEXTSTATE (1 << 17)
+
 /* old names; don't use in new code, but don't break them, either */
 #define OPf_LIST	OPf_WANT_LIST
 #define OPf_KNOW	OPf_WANT
diff --git a/perly.act b/perly.act
index 386cf3aefe16..e5022e1f930c 100644
--- a/perly.act
+++ b/perly.act
@@ -945,7 +945,7 @@ case 2: /* @1: %empty  */
                                 yyerror("A slurpy parameter may not have "
                                         "a default value");
 
-                            (yyval.opval) = var ? newSTATEOP(0, NULL, var) : NULL;
+                            (yyval.opval) = var ? newSTATEOP(OPf_FORCE_NEXTSTATE, NULL, var) : NULL;
                         }
 
     break;
@@ -1024,7 +1024,7 @@ case 2: /* @1: %empty  */
                                             "follows optional parameter");
                             }
 
-                            (yyval.opval) = var ? newSTATEOP(0, NULL, var) : NULL;
+                            (yyval.opval) = var ? newSTATEOP(OPf_FORCE_NEXTSTATE, NULL, var) : NULL;
                         }
 
     break;
@@ -1104,7 +1104,7 @@ case 2: /* @1: %empty  */
                                             (UNOP_AUX_item *)aux);
                             sigops = op_prepend_elem(OP_LINESEQ, check, sigops);
                             sigops = op_prepend_elem(OP_LINESEQ,
-                                                newSTATEOP(0, NULL, NULL),
+                                                newSTATEOP(OPf_FORCE_NEXTSTATE, NULL, NULL),
                                                 sigops);
                             /* a nextstate at the end handles context
                              * correctly for an empty sub body */
@@ -2331,6 +2331,6 @@ case 2: /* @1: %empty  */
     
 
 /* Generated from:
- * 9fc11f4af92f701d8d7909a9cd9dc52e01098c42c2504fb84c15e1d1e72f4803 perly.y
+ * 43bca65a61cd508da43f23047549ee0583ef762d0fa0cff9857d0038ac6eb083 perly.y
  * f13e9c08cea6302f0c1d1f467405bd0e0880d0ea92d0669901017a7f7e94ab28 regen_perly.pl
  * ex: set ro ft=c: */
diff --git a/perly.h b/perly.h
index 49877e206ea2..6442efb58d59 100644
--- a/perly.h
+++ b/perly.h
@@ -240,6 +240,6 @@ int yyparse (void);
 
 
 /* Generated from:
- * 9fc11f4af92f701d8d7909a9cd9dc52e01098c42c2504fb84c15e1d1e72f4803 perly.y
+ * 43bca65a61cd508da43f23047549ee0583ef762d0fa0cff9857d0038ac6eb083 perly.y
  * f13e9c08cea6302f0c1d1f467405bd0e0880d0ea92d0669901017a7f7e94ab28 regen_perly.pl
  * ex: set ro ft=c: */
diff --git a/perly.tab b/perly.tab
index 42292d0eb14b..5c40ee89ca2a 100644
--- a/perly.tab
+++ b/perly.tab
@@ -1569,6 +1569,6 @@ static const toketypes yy_type_tab[] =
 };
 
 /* Generated from:
- * 9fc11f4af92f701d8d7909a9cd9dc52e01098c42c2504fb84c15e1d1e72f4803 perly.y
+ * 43bca65a61cd508da43f23047549ee0583ef762d0fa0cff9857d0038ac6eb083 perly.y
  * f13e9c08cea6302f0c1d1f467405bd0e0880d0ea92d0669901017a7f7e94ab28 regen_perly.pl
  * ex: set ro ft=c: */
diff --git a/perly.y b/perly.y
index 6a6510823f0a..eeddba919395 100644
--- a/perly.y
+++ b/perly.y
@@ -837,7 +837,7 @@ sigslurpelem: sigslurpsigil sigvarname sigdefault/* def only to catch errors */
                                 yyerror("A slurpy parameter may not have "
                                         "a default value");
 
-                            $$ = var ? newSTATEOP(0, NULL, var) : NULL;
+                            $$ = var ? newSTATEOP(OPf_FORCE_NEXTSTATE, NULL, var) : NULL;
                         }
 	;
 
@@ -913,7 +913,7 @@ sigscalarelem:
                                             "follows optional parameter");
                             }
 
-                            $$ = var ? newSTATEOP(0, NULL, var) : NULL;
+                            $$ = var ? newSTATEOP(OPf_FORCE_NEXTSTATE, NULL, var) : NULL;
                         }
 	;
 
@@ -985,7 +985,7 @@ subsigguts:
                                             (UNOP_AUX_item *)aux);
                             sigops = op_prepend_elem(OP_LINESEQ, check, sigops);
                             sigops = op_prepend_elem(OP_LINESEQ,
-                                                newSTATEOP(0, NULL, NULL),
+                                                newSTATEOP(OPf_FORCE_NEXTSTATE, NULL, NULL),
                                                 sigops);
                             /* a nextstate at the end handles context
                              * correctly for an empty sub body */