diff --git a/src/lib/eolian_cxx/eo_validate.hh b/src/lib/eolian_cxx/eo_validate.hh
index 0b6f5cffca..8ffa7dccd7 100644
--- a/src/lib/eolian_cxx/eo_validate.hh
+++ b/src/lib/eolian_cxx/eo_validate.hh
@@ -71,10 +71,10 @@ eo_class_validate(const eo_class& cls)
 {
    // class name and type
    _validate(cls.name, cls);
-   assert(cls.type != eo_class::regular_ ||
-          cls.type != eo_class::regular_noninst_ ||
-          cls.type != eo_class::interface_ ||
-          cls.type != eo_class::mixin_);
+   assert(cls.type == eo_class::regular_ ||
+          cls.type == eo_class::regular_noninst_ ||
+          cls.type == eo_class::interface_ ||
+          cls.type == eo_class::mixin_);
 
    // constructors
    for (auto it = cls.constructors.cbegin(), last = cls.constructors.cend();