diff --git a/test/unordered/mmap_tests.cpp b/test/unordered/mmap_tests.cpp
index 73838544..c37400cf 100644
--- a/test/unordered/mmap_tests.cpp
+++ b/test/unordered/mmap_tests.cpp
@@ -298,6 +298,7 @@ std::string shm_name_sanitize(std::string const& exe_name)
     case '\\':
     case '-':
     case '_':
+    case '+':
       return true;
 
     default: