diff --git a/src/runtime/c/pgf/linearizer.cxx b/src/runtime/c/pgf/linearizer.cxx
index d44ca838f..fdf434f70 100644
--- a/src/runtime/c/pgf/linearizer.cxx
+++ b/src/runtime/c/pgf/linearizer.cxx
@@ -646,8 +646,14 @@ void PgfLinearizer::reverse_and_label(bool add_linref)
     }
 }
 
+PGF_INTERNAL_DECL bool
+pgf_is_case_sensitive(ref<PgfConcr> concr);
+
 void PgfLinearizer::flush_pre_stack(PgfLinearizationOutputIface *out, PgfText *token)
 {
+    bool (*cmp)(PgfText *t, PgfText *prefix) =
+        pgf_is_case_sensitive(concr) ? textstarts : textistarts;
+
     while (pre_stack != NULL) {
         PreStack *pre = pre_stack;
         pre_stack = pre->next;
@@ -657,7 +663,7 @@ void PgfLinearizer::flush_pre_stack(PgfLinearizationOutputIface *out, PgfText *t
                 PgfAlternative *alt = &pre->sym_kp->alts.data[i];
                 for (size_t j = 0; j < alt->prefixes->len; j++) {
                     ref<PgfText> prefix = *vector_elem(alt->prefixes,j);
-                    if (textstarts(token, &(*prefix))) {
+                    if (cmp(token, &(*prefix))) {
                         pre->node->linearize_seq(out, this, alt->form);
                         goto done;
                     }
diff --git a/src/runtime/c/pgf/pgf.cxx b/src/runtime/c/pgf/pgf.cxx
index bfd45e4d5..50c5e6f5e 100644
--- a/src/runtime/c/pgf/pgf.cxx
+++ b/src/runtime/c/pgf/pgf.cxx
@@ -819,7 +819,7 @@ void pgf_iter_lins(PgfDB *db, PgfConcrRevision cnc_revision,
     } PGF_API_END
 }
 
-static bool
+PGF_INTERNAL bool
 pgf_is_case_sensitive(ref<PgfConcr> concr)
 {
     PgfText *case_sensitive = (PgfText *)
diff --git a/src/runtime/c/pgf/text.cxx b/src/runtime/c/pgf/text.cxx
index d29126aa9..63a8b98eb 100644
--- a/src/runtime/c/pgf/text.cxx
+++ b/src/runtime/c/pgf/text.cxx
@@ -74,6 +74,29 @@ bool textstarts(PgfText *t, PgfText *prefix)
     return true;
 }
 
+PGF_INTERNAL
+bool textistarts(PgfText *t, PgfText *prefix)
+{
+    const uint8_t *s1 = (uint8_t*) &t->text;
+	const uint8_t *e1 = s1+t->size;
+
+	const uint8_t *s2 = (uint8_t*) &prefix->text;
+	const uint8_t *e2 = s2+prefix->size;
+
+    for (;;) {
+        if (s1 >= e1)
+            return false;
+        if (s2 >= e2)
+			return true;
+
+		uint32_t ucs1  = pgf_utf8_to_upper(pgf_utf8_decode(&s1));
+		uint32_t ucs2  = pgf_utf8_to_upper(pgf_utf8_decode(&s2));
+
+        if (ucs1 != ucs2)
+            return false;
+    }
+}
+
 PGF_INTERNAL
 PgfText* textdup(PgfText *t1)
 {
diff --git a/src/runtime/c/pgf/text.h b/src/runtime/c/pgf/text.h
index 31cf7f59c..919bea8e4 100644
--- a/src/runtime/c/pgf/text.h
+++ b/src/runtime/c/pgf/text.h
@@ -17,6 +17,9 @@ void texticmp(PgfText *t1, PgfText *t2, int res[2]);
 PGF_INTERNAL_DECL
 bool textstarts(PgfText *t, PgfText *prefix);
 
+PGF_INTERNAL
+bool textistarts(PgfText *t, PgfText *prefix);
+
 PGF_INTERNAL_DECL
 PgfText* string2text(const char *s);