--- src/hb-ot-map-private.hh
+++ src/hb-ot-map-private.hh
@@ -52,8 +52,11 @@
     unsigned int needs_fallback : 1;
     unsigned int auto_zwj : 1;
 
-    static int cmp (const feature_map_t *a, const feature_map_t *b)
-    { return a->tag < b->tag ? -1 : a->tag > b->tag ? 1 : 0; }
+    static int cmp (void const * a_, void const * b_) {
+      feature_map_t const * a = static_cast<feature_map_t const *>(a_);
+      feature_map_t const * b = static_cast<feature_map_t const *>(b_);
+      return a->tag < b->tag ? -1 : a->tag > b->tag ? 1 : 0;
+    }
   };
 
   struct lookup_map_t {
--- src/hb-ot-tag.cc
+++ src/hb-ot-tag.cc
@@ -778,9 +778,11 @@
 };
 
 static int
-lang_compare_first_component (const char *a,
-			      const char *b)
+lang_compare_first_component (void const * a_,
+			      void const * b_)
 {
+  char const * a = static_cast<char const *>(a_);
+  char const * b = static_cast<char const *>(b_);
   unsigned int da, db;
   const char *p;