2 files changed, 7 insertions, 1 deletions

diff --git a/src/keeper.c b/src/keeper.c
index a1505b7..1522718 100644
--- a/src/keeper.c
+++ b/src/keeper.c
@@ -810,7 +810,9 @@ int keeper_call( Universe* U, lua_State* K, keeper_api_t func_, lua_State* L, vo
     int const Ktos = lua_gettop( K);
     int retvals = -1;
 
-    STACK_GROW( K, 2);
+    // if we didn't do anything wrong, the keeper stack should be clean
+    ASSERT_L(Ktos == 0);
+    STACK_GROW(K, 2);
 
     PUSH_KEEPER_FUNC( K, func_);
 
diff --git a/src/linda.c b/src/linda.c
index 2128520..d92f5f2 100644
--- a/src/linda.c
+++ b/src/linda.c
@@ -90,12 +90,16 @@ LUAG_FUNC( linda_protected_call)
     Keeper* K = keeper_acquire( linda->U->keepers, LINDA_KEEPER_HASHSEED(linda));
     lua_State* KL = K ? K->L : NULL; // need to do this for 'STACK_CHECK'
     if( KL == NULL) return 0;
+    // if we didn't do anything wrong, the keeper stack should be clean
+    ASSERT_L(lua_gettop(KL) == 0);
 
     // retrieve the actual function to be called and move it before the arguments
     lua_pushvalue( L, lua_upvalueindex( 1));
     lua_insert( L, 1);
     // do a protected call
     rc = lua_pcall( L, lua_gettop( L) - 1, LUA_MULTRET, 0);
+    // whatever happens, the keeper state stack must be empty when we are done
+    lua_settop(KL, 0);
 
     // release the keeper
     keeper_release( K);