diff --git a/compiler/ncgutil.pas b/compiler/ncgutil.pas
index 4f12f78765..26fba4d55c 100644
--- a/compiler/ncgutil.pas
+++ b/compiler/ncgutil.pas
@@ -221,7 +221,13 @@ implementation
                  (fcl>0)) or
                 (((fcr=fcl) or
                   (fcr=0)) and
-                 (ncr>ncl)) then
+                 (ncr>ncl)) and
+                { if one tree contains nodes being conditionally executated, we cannot swap the trees
+                  as the other tree might depend on all nodes being executed, this applies for example
+                  for temp. create nodes with init part, they must be executed else things break, see
+                  issue #34653
+                }
+                 not(has_conditional_nodes(p.right)) then
                p.swapleftright
            end;
       end;
diff --git a/compiler/nutils.pas b/compiler/nutils.pas
index 7a2be2ea18..4276ccc61a 100644
--- a/compiler/nutils.pas
+++ b/compiler/nutils.pas
@@ -119,6 +119,9 @@ interface
     { returns true, if the tree given might have side effects }
     function might_have_sideeffects(n : tnode) : boolean;
 
+    { returns true, if n contains nodes which might be conditionally executed }
+    function has_conditional_nodes(n : tnode) : boolean;
+
     { count the number of nodes in the node tree,
       rough estimation how large the tree "node" is }
     function node_count(node : tnode) : dword;
@@ -1377,6 +1380,23 @@ implementation
         result:=foreachnodestatic(n,@check_for_sideeffect,nil);
       end;
 
+
+    function check_for_conditional_nodes(var n: tnode; arg: pointer): foreachnoderesult;
+      begin
+        result:=fen_false;
+        { this check is not complete yet, but sufficent to cover the current use case: swapping
+          of trees in expressions }
+        if (n.nodetype in [ifn,whilerepeatn,forn,tryexceptn]) or
+          ((n.nodetype in [orn,andn]) and is_boolean(n.resultdef) and doshortbooleval(n)) then
+          result:=fen_norecurse_true;
+      end;
+
+
+    function has_conditional_nodes(n : tnode) : boolean;
+      begin
+        result:=foreachnodestatic(n,@check_for_conditional_nodes,nil);
+      end;
+
     var
       nodecount : dword;
 
diff --git a/tests/webtbs/tw34653.pp b/tests/webtbs/tw34653.pp
new file mode 100644
index 0000000000..260dfd709f
--- /dev/null
+++ b/tests/webtbs/tw34653.pp
@@ -0,0 +1,22 @@
+{ %OPT=-O2 }
+var d: LongInt;
+begin
+    WriteLn;
+
+    d := 828;
+    if ((d mod 2) = 0) xor ((d < 0) and ((d mod 3) = 0)) then
+      WriteLn('YES')
+    else
+      begin
+        WriteLn('NO');
+        halt(1);
+      end;
+
+    if ((d mod 2) = 0) xor ((d < 0) and ((d mod 3) = 0)) then
+        WriteLn('YES')
+    else
+      begin
+        WriteLn('NO');
+        halt(1);
+      end;
+end.