diff --git a/src/calls.c b/src/calls.c
index 830f2ba28a..be94820394 100644
--- a/src/calls.c
+++ b/src/calls.c
@@ -957,6 +957,7 @@ Obj NewFunctionT (
     SET_NAME_FUNC(func, ConvImmString(name));
     SET_NARG_FUNC(func, narg);
     SET_NAMS_FUNC(func, nams);
+    SET_NLOC_FUNC(func, 0);
     if (nams) MakeBagPublic(nams);
     CHANGED_BAG(func);
 
@@ -1547,6 +1548,7 @@ Obj FuncPROFILE_FUNC(
         SET_NARG_FUNC(copy,   NARG_FUNC(func));
         SET_NAMS_FUNC(copy,   NAMS_FUNC(func));
         SET_PROF_FUNC(copy,   PROF_FUNC(func));
+        SET_NLOC_FUNC(copy,   NLOC_FUNC(func));
         SET_HDLR_FUNC(func,0, DoProf0args);
         SET_HDLR_FUNC(func,1, DoProf1args);
         SET_HDLR_FUNC(func,2, DoProf2args);
@@ -1730,14 +1732,14 @@ static ObjFunc LoadHandler( void )
 */
 void SaveFunction ( Obj func )
 {
-  FuncBag * header = FUNC(func);
+  const FuncBag * header = CONST_FUNC(func);
   for (UInt i = 0; i <= 7; i++)
     SaveHandler(header->handlers[i]);
   SaveSubObj(header->name);
-  SaveUInt(header->nargs);
+  SaveSubObj(header->nargs);
   SaveSubObj(header->namesOfLocals);
   SaveSubObj(header->prof);
-  SaveUInt(header->nloc);
+  SaveSubObj(header->nloc);
   SaveSubObj(header->body);
   SaveSubObj(header->envi);
   SaveSubObj(header->fexs);
@@ -1756,10 +1758,10 @@ void LoadFunction ( Obj func )
   for (UInt i = 0; i <= 7; i++)
     header->handlers[i] = LoadHandler();
   header->name = LoadSubObj();
-  header->nargs = LoadUInt();
+  header->nargs = LoadSubObj();
   header->namesOfLocals = LoadSubObj();
   header->prof = LoadSubObj();
-  header->nloc = LoadUInt();
+  header->nloc = LoadSubObj();
   header->body = LoadSubObj();
   header->envi = LoadSubObj();
   header->fexs = LoadSubObj();
@@ -1769,6 +1771,21 @@ void LoadFunction ( Obj func )
 
 #endif
 
+/****************************************************************************
+**
+*F  MarkFunctionSubBags( <bag> ) . . . . . . . marking function for functions
+**
+**  'MarkFunctionSubBags' is the marking function for bags of type 'T_FUNCTION'.
+*/
+void MarkFunctionSubBags(Obj func)
+{
+    // the first eight slots are pointers to C functions, so we need
+    // to skip those for marking
+    UInt size = SIZE_BAG(func) / sizeof(Obj) - 8;
+    const Bag * data = CONST_PTR_BAG(func) + 8;
+    MarkArrayOfBags(data, size);
+}
+
 
 /****************************************************************************
 **
@@ -1836,7 +1853,7 @@ static Int InitKernel (
   
     /* install the marking functions                                       */
     InfoBags[ T_FUNCTION ].name = "function";
-    InitMarkFuncBags( T_FUNCTION , MarkAllSubBags );
+    InitMarkFuncBags(T_FUNCTION, MarkFunctionSubBags);
 
     /* Allocate functions in the public region */
     MakeBagTypePublic(T_FUNCTION);
diff --git a/src/calls.h b/src/calls.h
index 593f048877..1b44eeed2d 100644
--- a/src/calls.h
+++ b/src/calls.h
@@ -107,10 +107,10 @@ typedef Obj (* ObjFunc_6ARGS) (Obj self, Obj a1, Obj a2, Obj a3, Obj a4, Obj a5,
 typedef struct {
     ObjFunc handlers[8];
     Obj name;
-    Int nargs;
+    Obj nargs;
     Obj namesOfLocals;
     Obj prof;
-    UInt nloc;
+    Obj nloc;
     Obj body;
     Obj envi;
     Obj fexs;
@@ -146,7 +146,7 @@ static inline Obj NAME_FUNC(Obj func)
 
 static inline Int NARG_FUNC(Obj func)
 {
-    return CONST_FUNC(func)->nargs;
+    return INT_INTOBJ(CONST_FUNC(func)->nargs);
 }
 
 static inline Obj NAMS_FUNC(Obj func)
@@ -163,7 +163,7 @@ static inline Obj PROF_FUNC(Obj func)
 
 static inline UInt NLOC_FUNC(Obj func)
 {
-    return CONST_FUNC(func)->nloc;
+    return INT_INTOBJ(CONST_FUNC(func)->nloc);
 }
 
 static inline Obj BODY_FUNC(Obj func)
@@ -199,7 +199,7 @@ extern void SET_NAME_FUNC(Obj func, Obj name);
 
 static inline void SET_NARG_FUNC(Obj func, Int nargs)
 {
-    FUNC(func)->nargs = nargs;
+    FUNC(func)->nargs = INTOBJ_INT(nargs);
 }
 
 static inline void SET_NAMS_FUNC(Obj func, Obj namesOfLocals)
@@ -214,7 +214,7 @@ static inline void SET_PROF_FUNC(Obj func, Obj prof)
 
 static inline void SET_NLOC_FUNC(Obj func, UInt nloc)
 {
-    FUNC(func)->nloc = nloc;
+    FUNC(func)->nloc = INTOBJ_INT(nloc);
 }
 
 static inline void SET_BODY_FUNC(Obj func, Obj body)
diff --git a/src/opers.c b/src/opers.c
index 9470c70d64..e9acf8429f 100644
--- a/src/opers.c
+++ b/src/opers.c
@@ -3313,22 +3313,22 @@ void InstallGlobalFunction (
 void SaveOperationExtras (
     Obj         oper )
 {
-    UInt        i;
-
-    SaveSubObj(FLAG1_FILT(oper));
-    SaveSubObj(FLAG2_FILT(oper));
-    SaveSubObj(FLAGS_FILT(oper));
-    SaveSubObj(SETTR_FILT(oper));
-    SaveSubObj(TESTR_FILT(oper));
-    SaveUInt(ENABLED_ATTR(oper));
-    for (i = 0; i <= 7; i++)
-        SaveSubObj(METHS_OPER(oper,i));
+    const OperBag * header = CONST_OPER(oper);
+
+    SaveSubObj(header->flag1);
+    SaveSubObj(header->flag2);
+    SaveSubObj(header->flags);
+    SaveSubObj(header->setter);
+    SaveSubObj(header->tester);
+    SaveSubObj(header->enabled);
+    for (UInt i = 0; i <= 7; i++)
+        SaveSubObj(header->methods[i]);
 #ifdef HPCGAP
     // FIXME: We probably don't want to save/restore the cache?
     // (and that would include "normal" GAP, too...)
 #else
-    for (i = 0; i <= 7; i++)
-        SaveSubObj(CACHE_OPER(oper,i));
+    for (UInt i = 0; i <= 7; i++)
+        SaveSubObj(header->cache[i]);
 #endif
 }
 
@@ -3344,23 +3344,22 @@ void SaveOperationExtras (
 void LoadOperationExtras (
     Obj         oper )
 {
-    UInt        i;
-
-    SET_FLAG1_FILT(oper, LoadSubObj());
-    SET_FLAG2_FILT(oper, LoadSubObj());
-    SET_FLAGS_FILT(oper, LoadSubObj());
-    SET_SETTR_FILT(oper, LoadSubObj());
-    SET_TESTR_FILT(oper, LoadSubObj());
-    i = LoadUInt();
-    SET_ENABLED_ATTR(oper,i);
-    for (i = 0; i <= 7; i++)
-        SET_METHS_OPER(oper, i, LoadSubObj());
+    OperBag * header = OPER(oper);
+
+    header->flag1 = LoadSubObj();
+    header->flag2 = LoadSubObj();
+    header->flags = LoadSubObj();
+    header->setter = LoadSubObj();
+    header->tester = LoadSubObj();
+    header->enabled = LoadSubObj();
+    for (UInt i = 0; i <= 7; i++)
+        header->methods[i] = LoadSubObj();
 #ifdef HPCGAP
     // FIXME: We probably don't want to save/restore the cache?
     // (and that would include "normal" GAP, too...)
 #else
-    for (i = 0; i <= 7; i++)
-        SET_CACHE_OPER(oper, i, LoadSubObj());
+    for (UInt i = 0; i <= 7; i++)
+        header->cache[i] = LoadSubObj();
 #endif
 }