diff --git a/src/base/ctexceptions.cpp b/src/base/ctexceptions.cpp
index 7f1b610dc..118f8e173 100644
--- a/src/base/ctexceptions.cpp
+++ b/src/base/ctexceptions.cpp
@@ -72,6 +72,9 @@ string ArraySizeError::getMessage() const
 
 string IndexError::getMessage() const
 {
+    if (arrayName_ == "") {
+        return fmt::format("IndexError: {} outside valid range of 0 to {}.", m_, mmax_);
+    }
     return fmt::format("IndexError: {}[{}] outside valid range of 0 to {}.",
                        arrayName_, m_, mmax_);
 }