diff --git a/dace/transformation/passes/constant_propagation.py b/dace/transformation/passes/constant_propagation.py
index 19e17066fa..d95b72ab28 100644
--- a/dace/transformation/passes/constant_propagation.py
+++ b/dace/transformation/passes/constant_propagation.py
@@ -369,6 +369,14 @@ def _collect_constants_for_region(self, cfg: ControlFlowRegion, arrays: Set[str]
                         if reassignments and (used_in_assignments - reassignments):
                             assignments[aname] = _UnknownValue
 
+                if isinstance(block, LoopRegion):
+                    # Any constants before a loop that may be overwritten inside the loop cannot be assumed as constants
+                    # for the loop itself.
+                    assigned_in_loop = self._assignments_in_loop(block)
+                    for k in assignments.keys():
+                        if k in assigned_in_loop:
+                            assignments[k] = _UnknownValue
+
                 if block not in in_const_dict:
                     in_const_dict[block] = {}
                 if assignments: