diff --git a/src/cairo-mutex-impl-private.h b/src/cairo-mutex-impl-private.h
index 25fee4b63..52519076b 100644
--- a/src/cairo-mutex-impl-private.h
+++ b/src/cairo-mutex-impl-private.h
@@ -47,6 +47,11 @@
 #include "config.h"
 #endif
 
+#if HAVE_LOCKDEP
+#include <lockdep.h>
+#endif
+
+CAIRO_BEGIN_DECLS
 
 /* A fully qualified no-operation statement */
 #define CAIRO_MUTEX_IMPL_NOOP	do {/*no-op*/} while (0)
@@ -171,10 +176,19 @@
   typedef pthread_mutex_t cairo_mutex_impl_t;
 
 # define CAIRO_MUTEX_IMPL_PTHREAD 1
+#if HAVE_LOCKDEP
+/* expose all mutexes to the validator */
+# define CAIRO_MUTEX_IMPL_INIT(mutex) pthread_mutex_init (&(mutex), NULL)
+#endif
 # define CAIRO_MUTEX_IMPL_LOCK(mutex) pthread_mutex_lock (&(mutex))
 # define CAIRO_MUTEX_IMPL_UNLOCK(mutex) pthread_mutex_unlock (&(mutex))
+#if HAVE_LOCKDEP
+# define CAIRO_HOLDS_MUTEX(mutex) LOCKDEP_HOLDS_LOCK (&(mutex))
+#endif
 # define CAIRO_MUTEX_IMPL_FINI(mutex) pthread_mutex_destroy (&(mutex))
+#if ! HAVE_LOCKDEP
 # define CAIRO_MUTEX_IMPL_FINALIZE() CAIRO_MUTEX_IMPL_NOOP
+#endif
 # define CAIRO_MUTEX_IMPL_NIL_INITIALIZER PTHREAD_MUTEX_INITIALIZER
 
 #elif defined(HAVE_WINDOWS_H) || defined(_MSC_VER) /*************************/
diff --git a/src/cairo-mutex-type-private.h b/src/cairo-mutex-type-private.h
index 2314be1d0..776b0db28 100644
--- a/src/cairo-mutex-type-private.h
+++ b/src/cairo-mutex-type-private.h
@@ -44,6 +44,8 @@
 #include "cairo-compiler-private.h"
 #include "cairo-mutex-impl-private.h"
 
+CAIRO_BEGIN_DECLS
+
 /* Only the following three are mandatory at this point */
 #ifndef CAIRO_MUTEX_IMPL_LOCK
 # error "CAIRO_MUTEX_IMPL_LOCK not defined.  Check cairo-mutex-impl-private.h."
@@ -90,7 +92,6 @@
 
 #endif /* CAIRO_MUTEX_IMPL_INIT */
 
-
 #ifdef CAIRO_MUTEX_IMPL_FINI
 
 /* If %CAIRO_MUTEX_IMPL_FINI is defined, we may need to finalize all
@@ -169,6 +170,9 @@ typedef cairo_mutex_impl_t cairo_mutex_t;
 #define CAIRO_MUTEX_FINI		CAIRO_MUTEX_IMPL_FINI
 #define CAIRO_MUTEX_NIL_INITIALIZER	CAIRO_MUTEX_IMPL_NIL_INITIALIZER
 
+#ifndef CAIRO_HOLDS_MUTEX
+# define CAIRO_HOLDS_MUTEX(name) 1
+#endif
 
 
 /* Debugging support */
diff --git a/src/cairo-scaled-font.c b/src/cairo-scaled-font.c
index bfe076a1f..fcea8aa9e 100644
--- a/src/cairo-scaled-font.c
+++ b/src/cairo-scaled-font.c
@@ -656,18 +656,24 @@ _cairo_scaled_font_init (cairo_scaled_font_t               *scaled_font,
 void
 _cairo_scaled_font_freeze_cache (cairo_scaled_font_t *scaled_font)
 {
+    assert (CAIRO_HOLDS_MUTEX (scaled_font->mutex));
+
     _cairo_cache_freeze (scaled_font->glyphs);
 }
 
 void
 _cairo_scaled_font_thaw_cache (cairo_scaled_font_t *scaled_font)
 {
+    assert (CAIRO_HOLDS_MUTEX (scaled_font->mutex));
+
     _cairo_cache_thaw (scaled_font->glyphs);
 }
 
 void
 _cairo_scaled_font_reset_cache (cairo_scaled_font_t *scaled_font)
 {
+    assert (CAIRO_HOLDS_MUTEX (scaled_font->mutex));
+
     _cairo_cache_destroy (scaled_font->glyphs);
     scaled_font->glyphs = _cairo_cache_create (_cairo_scaled_glyph_keys_equal,
 					       _cairo_scaled_glyph_destroy,
@@ -1689,6 +1695,8 @@ _cairo_scaled_font_glyph_device_extents (cairo_scaled_font_t	 *scaled_font,
     if (scaled_font->status)
 	return scaled_font->status;
 
+    assert (CAIRO_HOLDS_MUTEX (scaled_font->mutex));
+
     for (i = 0; i < num_glyphs; i++) {
 	cairo_scaled_glyph_t	*scaled_glyph;
 	int			left, top;
@@ -1760,6 +1768,7 @@ _cairo_scaled_font_show_glyphs (cairo_scaled_font_t    *scaled_font,
     if (!num_glyphs)
 	return CAIRO_STATUS_SUCCESS;
 
+    assert (CAIRO_HOLDS_MUTEX (scaled_font->mutex));
     if (scaled_font->backend->show_glyphs != NULL) {
 	int remaining_glyphs = num_glyphs;
 	status = scaled_font->backend->show_glyphs (scaled_font,
@@ -2074,6 +2083,8 @@ _cairo_scaled_font_glyph_path (cairo_scaled_font_t *scaled_font,
     if (status)
 	return status;
 
+    assert (CAIRO_HOLDS_MUTEX (scaled_font->mutex));
+
     closure.path = path;
     _cairo_scaled_font_freeze_cache (scaled_font);
     for (i = 0; i < num_glyphs; i++) {
@@ -2284,6 +2295,8 @@ _cairo_scaled_glyph_lookup (cairo_scaled_font_t *scaled_font,
     if (scaled_font->status)
 	return scaled_font->status;
 
+    assert (CAIRO_HOLDS_MUTEX (scaled_font->mutex));
+
     key.hash = index;
     /*
      * Check cache for glyph