diff --git a/src/Makefile.am b/src/Makefile.am
index 2a3d6c79aa7f45c6f1c11f6be2c67fb9987f7425..839f8997ac8f41090753eb3d774396d0c432dc76 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -130,7 +130,7 @@ pkgconfig_DATA = harfbuzz.pc
 EXTRA_DIST += harfbuzz.pc.in
 
 FUZZING_CPPFLAGS= \
-	-DNDEBUG \
+	-DHB_NDEBUG \
 	-DHB_MAX_NESTING_LEVEL=3 \
 	-DHB_SANITIZE_MAX_EDITS=3 \
 	-DHB_BUFFER_MAX_EXPANSION_FACTOR=3 \
diff --git a/src/hb-buffer-private.hh b/src/hb-buffer-private.hh
index c3184cf7653e49f51a2a8d0f153c030f9c159534..fee5949803f95d90ff20d12298d68e9714695b37 100644
--- a/src/hb-buffer-private.hh
+++ b/src/hb-buffer-private.hh
@@ -124,7 +124,7 @@ struct hb_buffer_t {
   void *message_data;
   hb_destroy_func_t message_destroy;
 
-#ifndef NDEBUG
+#ifndef HB_NDEBUG
   /* Internal debugging. */
   /* These reflect current allocations of the bytes in glyph_info_t's var1 and var2. */
   uint8_t allocated_var_bytes[8];
@@ -260,7 +260,7 @@ struct hb_buffer_t {
 #define HB_BUFFER_XALLOCATE_VAR(b, func, var, owner) \
   b->func (offsetof (hb_glyph_info_t, var) - offsetof(hb_glyph_info_t, var1), \
 	   sizeof (b->info[0].var), owner)
-#ifndef NDEBUG
+#ifndef HB_NDEBUG
 #define HB_BUFFER_ALLOCATE_VAR(b, var) \
 	HB_BUFFER_XALLOCATE_VAR (b, allocate_var, var (), #var)
 #define HB_BUFFER_DEALLOCATE_VAR(b, var) \
diff --git a/src/hb-buffer.cc b/src/hb-buffer.cc
index ea2a70d5b07e7feeeeb7cab56f5e1c486f387428..ea639559fc595bd76b758c63c7c1d6e9e46f7fec 100644
--- a/src/hb-buffer.cc
+++ b/src/hb-buffer.cc
@@ -661,7 +661,7 @@ hb_buffer_t::guess_segment_properties (void)
 }
 
 
-#ifndef NDEBUG
+#ifndef HB_NDEBUG
 static inline void
 dump_var_allocation (const hb_buffer_t *buffer)
 {
@@ -729,7 +729,7 @@ void hb_buffer_t::deallocate_var_all (void)
   memset (allocated_var_bytes, 0, sizeof (allocated_var_bytes));
   memset (allocated_var_owner, 0, sizeof (allocated_var_owner));
 }
-#endif /* NDEBUG */
+#endif /* HB_NDEBUG */
 
 /* Public API */
 
diff --git a/src/hb-private.hh b/src/hb-private.hh
index 7afb25803fb0fa69c315279c51d05870dd22c42a..179e4e9f7418f487475809ef6449b0ef775d54e3 100644
--- a/src/hb-private.hh
+++ b/src/hb-private.hh
@@ -611,6 +611,15 @@ static inline unsigned char TOLOWER (unsigned char c)
 /* Debug */
 
 
+/* HB_NDEBUG disables some sanity checks that are very safe to disable and
+ * should be disabled in production systems.  If NDEBUG is defined, enable
+ * HB_NDEBUG; but if it's desirable that normal assert()s (which are very
+ * light-weight) to be enabled, then HB_DEBUG can be defined to disable
+ * the costlier checks. */
+#ifdef NDEBUG
+#define HB_NDEBUG
+#endif
+
 #ifndef HB_DEBUG
 #define HB_DEBUG 0
 #endif