diff --git a/libs/main/core/pibase.h b/libs/main/core/pibase.h
index cf01c16f..451168a9 100644
--- a/libs/main/core/pibase.h
+++ b/libs/main/core/pibase.h
@@ -963,9 +963,10 @@ inline uint piHash(const ldouble & v) {
 }
 
 template<typename T>
-inline void piDeleteAll(T & container) {
-	for (auto i: container)
+inline void piDeleteAll(const T & container) {
+	for (auto i: container) {
 		delete i;
+	}
 }
 template<typename T>
 inline void piDeleteAllAndClear(T & container) {