diff --git a/php/src/exceptions.php b/php/src/exceptions.php
index 8bfcb9f..a6b1e88 100644
--- a/php/src/exceptions.php
+++ b/php/src/exceptions.php
@@ -14,7 +14,8 @@ class exceptions {
     if ($e instanceof UserException) $userMessage = $e->getUserMessage();
     elseif ($e instanceof ExceptionShadow) $userMessage = $e->getUserMessage();
     else return null;
-    return c::to_string($userMessage);
+    if ($userMessage === null) return null;
+    else return c::to_string($userMessage);
   }
 
   /** @param Throwable|ExceptionShadow $e */
@@ -22,7 +23,8 @@ class exceptions {
     if ($e instanceof UserException) $techMessage = $e->getTechMessage();
     elseif ($e instanceof ExceptionShadow) $techMessage = $e->getTechMessage();
     else return null;
-    return c::to_string($techMessage);
+    if ($techMessage === null) return null;
+    else return c::to_string($techMessage);
   }
 
   /** @param Throwable|ExceptionShadow $e */