diff --git a/CHANGELOG.md b/CHANGELOG.md
index fbec1d025..a243f784b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -8,6 +8,7 @@
 - Fixed incorrect `getObjVal()` result when called before `getBestSol()` (e.g., in event handlers).
 ### Changed
 - Replaced `format()` with f-strings in examples
+- Made expression fields read-only to prevent accidental runtime modification
 ### Removed
 
 ## 6.3.0 - 2026.10.11
diff --git a/src/pyscipopt/expr.pxi b/src/pyscipopt/expr.pxi
index 73743a969..3886df3d4 100644
--- a/src/pyscipopt/expr.pxi
+++ b/src/pyscipopt/expr.pxi
@@ -573,7 +573,7 @@ Operator = Op()
 cdef class GenExpr(ExprLike):
 
     cdef public _op
-    cdef public children
+    cdef readonly children
 
     def __init__(self): # do we need it
         ''' '''
@@ -749,7 +749,7 @@ cdef class GenExpr(ExprLike):
 # Sum Expressions
 cdef class SumExpr(GenExpr):
 
-    cdef public constant
+    cdef readonly constant
 
     def __init__(self):
         self.constant = 0.0
@@ -778,7 +778,7 @@ cdef class SumExpr(GenExpr):
 # Prod Expressions
 cdef class ProdExpr(GenExpr):
 
-    cdef public constant
+    cdef readonly constant
 
     def __init__(self):
         self.constant = 1.0
@@ -830,7 +830,7 @@ cdef class VarExpr(GenExpr):
 # Pow Expressions
 cdef class PowExpr(GenExpr):
 
-    cdef public expo
+    cdef readonly expo
 
     def __init__(self):
         self.expo = 1.0
@@ -929,7 +929,7 @@ cdef class CosExpr(UnaryExpr):
 
 cdef class Constant(GenExpr):
 
-    cdef public number
+    cdef readonly number
 
     def __init__(self, number: Union[int, float]):
         self.number = number
diff --git a/src/pyscipopt/scip.pxd b/src/pyscipopt/scip.pxd
index fe5f3ac6b..6fbeaf08a 100644
--- a/src/pyscipopt/scip.pxd
+++ b/src/pyscipopt/scip.pxd
@@ -2192,7 +2192,7 @@ cdef class ExprLike:
     cdef ExprLike copy(self, bint copy=*)
 
 cdef class Expr(ExprLike):
-    cdef public terms
+    cdef readonly terms
 
 cdef class Event:
     cdef SCIP_EVENT* event
diff --git a/src/pyscipopt/scip.pyi b/src/pyscipopt/scip.pyi
index a29999dc1..dbc20b1e1 100644
--- a/src/pyscipopt/scip.pyi
+++ b/src/pyscipopt/scip.pyi
@@ -251,7 +251,8 @@ class Conshdlr:
 
 @disjoint_base
 class Constant(GenExpr):
-    number: SupportsFloat
+    @property
+    def number(self) -> SupportsFloat: ...
     def __init__(self, number: SupportsFloat) -> None: ...
     def __neg__(self, /) -> Constant: ...
     def __pow__(  # type: ignore[override]
@@ -379,7 +380,8 @@ class ExprLike:
 
 @disjoint_base
 class Expr(ExprLike):
-    terms: Incomplete
+    @property
+    def terms(self) -> dict[Term, float]: ...
     def __init__(self, terms: Incomplete = None) -> None: ...
     def degree(self) -> int: ...
     def normalize(self) -> None: ...
@@ -443,7 +445,8 @@ class ExprCons:
 @disjoint_base
 class GenExpr(ExprLike):
     _op: str | None
-    children: Incomplete
+    @property
+    def children(self) -> list[GenExpr]: ...
     def __init__(self) -> None: ...
     def degree(self) -> float: ...
     @deprecated("Deprecated since 6.3.0; use type(expr) instead.")
@@ -2144,7 +2147,8 @@ class PY_SCIP_STATUS:
 
 @disjoint_base
 class PowExpr(GenExpr):
-    expo: SupportsFloat
+    @property
+    def expo(self) -> SupportsFloat: ...
     def __init__(self) -> None: ...
     def __neg__(self, /) -> ProdExpr: ...
 
@@ -2175,7 +2179,8 @@ class Pricer:
 
 @disjoint_base
 class ProdExpr(GenExpr):
-    constant: SupportsFloat
+    @property
+    def constant(self) -> SupportsFloat: ...
     def __init__(self) -> None: ...
     def __neg__(self, /) -> ProdExpr: ...
 
@@ -2374,7 +2379,8 @@ class Statistics:
 
 @disjoint_base
 class SumExpr(GenExpr):
-    constant: SupportsFloat
+    @property
+    def constant(self) -> SupportsFloat: ...
     def __init__(self) -> None: ...
     def __neg__(self, /) -> ProdExpr: ...