diff --git a/libasn1compiler/asn1c_C.c b/libasn1compiler/asn1c_C.c
index 73ccbdd..e2aece2 100644
--- a/libasn1compiler/asn1c_C.c
+++ b/libasn1compiler/asn1c_C.c
@@ -2625,8 +2625,10 @@
     if(expr->meta_type != AMT_TYPEREF
        || expr->expr_type != A1TC_REFERENCE
        || expr->reference->comp_count != 2
-       || expr->reference->components[1].lex_type
-              != RLT_AmpUppercase) {
+       || ((expr->reference->components[1].lex_type
+              != RLT_AmpUppercase)
+            && (expr->reference->components[1].lex_type
+                   != RLT_Amplowercase))) {
         FATAL(
             "Does not look like %s is a CLASS field reference (%s) denoting a type on line "
             "%d",