diff --git a/src/Collections/List.hpp b/src/Collections/List.hpp
index 1cc59df..a87bcda 100644
--- a/src/Collections/List.hpp
+++ b/src/Collections/List.hpp
@@ -35,7 +35,7 @@ namespace ArbUt {
 #ifndef NO_ASSERT
             if (index >= _vector.size()) {
                 std::stringstream ss;
-                ss << "Index " << index << " is out of bounds.";
+                ss << "Index " << index << " is out of bounds for length: " << _vector.size();
                 throw ArbUt::Exception(ss.str());
             }
 #endif
@@ -49,7 +49,7 @@ namespace ArbUt {
 #ifndef NO_ASSERT
             if (index >= _vector.size()) {
                 std::stringstream ss;
-                ss << "Index " << index << " is out of bounds.";
+                ss << "Index " << index << " is out of bounds for length: " << _vector.size();
                 throw ArbUt::Exception(ss.str());
             }
 #endif
@@ -64,7 +64,7 @@ namespace ArbUt {
 #ifndef NO_ASSERT
             if (index >= _vector.size()) {
                 std::stringstream ss;
-                ss << "Index " << index << " is out of bounds.";
+                ss << "Index " << index << " is out of bounds for length: " << _vector.size();
                 throw ArbUt::Exception(ss.str());
             }
 #endif
diff --git a/src/Memory/__OptionalUniquePtrList.hpp b/src/Memory/__OptionalUniquePtrList.hpp
index f6ca1a8..2da5a6c 100644
--- a/src/Memory/__OptionalUniquePtrList.hpp
+++ b/src/Memory/__OptionalUniquePtrList.hpp
@@ -48,7 +48,7 @@ namespace ArbUt {
 #ifndef NO_ASSERT
             if (index >= _vector.size()) {
                 std::stringstream ss;
-                ss << "Index " << index << " is out of bounds.";
+                ss << "Index " << index << " is out of bounds for length: " << _vector.size();
                 throw ArbUt::Exception(ss.str());
             }
 #endif
@@ -86,7 +86,7 @@ namespace ArbUt {
 #ifndef NO_ASSERT
             if (index >= _vector.size()) {
                 std::stringstream ss;
-                ss << "Index " << index << " is out of bounds.";
+                ss << "Index " << index << " is out of bounds for length: " << _vector.size();
                 throw ArbUt::Exception(ss.str());
             }
 #endif
diff --git a/src/Memory/__UniquePtrList.hpp b/src/Memory/__UniquePtrList.hpp
index 1322488..cb6555e 100644
--- a/src/Memory/__UniquePtrList.hpp
+++ b/src/Memory/__UniquePtrList.hpp
@@ -53,7 +53,7 @@ namespace ArbUt {
 #ifndef NO_ASSERT
             if (index >= _vector.size()) {
                 std::stringstream ss;
-                ss << "Index " << index << " is out of bounds.";
+                ss << "Index " << index << " is out of bounds for length: " << _vector.size();
                 throw ArbUt::Exception(ss.str());
             }
 #endif
@@ -92,7 +92,7 @@ namespace ArbUt {
 #ifndef NO_ASSERT
             if (index >= _vector.size()) {
                 std::stringstream ss;
-                ss << "Index " << index << " is out of bounds.";
+                ss << "Index " << index << " is out of bounds for length: " << _vector.size();
                 throw ArbUt::Exception(ss.str());
             }
 #endif