diff --git a/extensions/openpower-pels/ascii_string.cpp b/extensions/openpower-pels/ascii_string.cpp
index 124bd0c..7d4d4f3 100644
--- a/extensions/openpower-pels/ascii_string.cpp
+++ b/extensions/openpower-pels/ascii_string.cpp
@@ -73,6 +73,15 @@
 void AsciiString::unflatten(Stream& stream)
 {
     stream.read(_string.data(), _string.size());
+
+    // Only allow certain ASCII characters as other entities will
+    // eventually want to display this.
+    std::for_each(_string.begin(), _string.end(), [](auto& c) {
+        if (!isalnum(c) && (c != ' ') && (c != '.') && (c != ':') && (c != '/'))
+        {
+            c = ' ';
+        }
+    });
 }
 
 std::string AsciiString::get() const