diff --git a/js/src/jsinterp.c b/js/src/jsinterp.c
index b7c572886388..184005a236da 100644
--- a/js/src/jsinterp.c
+++ b/js/src/jsinterp.c
@@ -2326,6 +2326,12 @@ js_Interpret(JSContext *cx, jsval *result)
             vp = &sp[i - 1];
             rval = *vp;
 
+            /*
+             * Save sp in fp now, before any OBJ_* call-outs that might nest
+             * an interpreter or GC activation on this context.
+             */
+            SAVE_SP(fp);
+
             /* Is this the first iteration ? */
             if (JSVAL_IS_VOID(rval)) {
                 /* Yes, create a new JSObject to hold the iterator state */
@@ -2589,6 +2595,7 @@ js_Interpret(JSContext *cx, jsval *result)
             obj = fp->varobj;
             atom = GET_ATOM(cx, script, pc);
             rval = FETCH_OPND(-1);
+            SAVE_SP(fp);
             ok = OBJ_DEFINE_PROPERTY(cx, obj, ATOM_TO_JSID(atom), rval,
                                      NULL, NULL,
                                      JSPROP_ENUMERATE | JSPROP_PERMANENT |
@@ -2989,6 +2996,7 @@ js_Interpret(JSContext *cx, jsval *result)
 #if JS_HAS_INITIALIZERS
           do_new:
 #endif
+            SAVE_SP(fp);
             vp = sp - (2 + argc);
             JS_ASSERT(vp >= fp->spbase);
 
@@ -3001,7 +3009,6 @@ js_Interpret(JSContext *cx, jsval *result)
                 OBJ_GET_CLASS(cx, obj2) == &js_FunctionClass ||
                 !obj2->map->ops->construct)
             {
-                SAVE_SP(fp);
                 fun = js_ValueToFunction(cx, vp, JSV2F_CONSTRUCT);
                 if (!fun) {
                     ok = JS_FALSE;
@@ -3038,7 +3045,6 @@ js_Interpret(JSContext *cx, jsval *result)
 
             /* Now we have an object with a constructor method; call it. */
             vp[1] = OBJECT_TO_JSVAL(obj);
-            SAVE_SP(fp);
             ok = js_Invoke(cx, argc, JSINVOKE_CONSTRUCT);
             RESTORE_SP(fp);
             LOAD_BRANCH_CALLBACK(cx);
@@ -3938,6 +3944,7 @@ js_Interpret(JSContext *cx, jsval *result)
 
 #if JS_HAS_EXPORT_IMPORT
           case JSOP_EXPORTALL:
+            SAVE_SP(fp);
             obj = fp->varobj;
             ida = JS_Enumerate(cx, obj);
             if (!ida) {
@@ -3967,6 +3974,7 @@ js_Interpret(JSContext *cx, jsval *result)
             atom = GET_ATOM(cx, script, pc);
             id   = ATOM_TO_JSID(atom);
             obj  = fp->varobj;
+            SAVE_SP(fp);
             ok = OBJ_LOOKUP_PROPERTY(cx, obj, id, &obj2, &prop);
             if (!ok)
                 goto out;
@@ -4440,6 +4448,7 @@ js_Interpret(JSContext *cx, jsval *result)
              * have seen the right parent already and created a sufficiently
              * well-scoped function object.
              */
+            SAVE_SP(fp);
             parent = fp->scopeChain;
             if (OBJ_GET_PARENT(cx, obj) != parent) {
                 obj = js_CloneFunctionObject(cx, obj, parent);
@@ -4552,6 +4561,7 @@ js_Interpret(JSContext *cx, jsval *result)
              * Getters and setters are just like watchpoints from an access
              * control point of view.
              */
+            SAVE_SP(fp);
             ok = OBJ_CHECK_ACCESS(cx, obj, id, JSACC_WATCH, &rtmp, &attrs);
             if (!ok)
                 goto out;
@@ -4627,6 +4637,7 @@ js_Interpret(JSContext *cx, jsval *result)
             obj = JSVAL_TO_OBJECT(lval);
 
             /* Set the property named by obj[id] to rval. */
+            SAVE_SP(fp);
             ok = OBJ_SET_PROPERTY(cx, obj, id, &rval);
             if (!ok)
                 goto out;
@@ -4635,6 +4646,7 @@ js_Interpret(JSContext *cx, jsval *result)
 
 #if JS_HAS_SHARP_VARS
           case JSOP_DEFSHARP:
+            SAVE_SP(fp);
             obj = fp->sharpArray;
             if (!obj) {
                 obj = js_NewArrayObject(cx, 0, NULL);
@@ -4667,6 +4679,7 @@ js_Interpret(JSContext *cx, jsval *result)
             if (!obj) {
                 rval = JSVAL_VOID;
             } else {
+                SAVE_SP(fp);
                 ok = OBJ_GET_PROPERTY(cx, obj, id, &rval);
                 if (!ok)
                     goto out;
@@ -4743,6 +4756,7 @@ js_Interpret(JSContext *cx, jsval *result)
             obj = JSVAL_TO_OBJECT(lval);
 
             /* Define obj[id] to contain rval and to be permanent. */
+            SAVE_SP(fp);
             ok = OBJ_DEFINE_PROPERTY(cx, obj, id, rval, NULL, NULL,
                                      JSPROP_PERMANENT, NULL);
             if (!ok)