diff --git a/builtin/grep.c b/builtin/grep.c
index 8e928e2170..b194ea3cea 100644
--- a/builtin/grep.c
+++ b/builtin/grep.c
@@ -17,8 +17,8 @@
 #include "dir.h"
 
 #ifndef NO_PTHREADS
-#include "thread-utils.h"
 #include <pthread.h>
+#include "thread-utils.h"
 #endif
 
 static char const * const grep_usage[] = {
diff --git a/builtin/pack-objects.c b/builtin/pack-objects.c
index 97802585ea..214d7ef2b1 100644
--- a/builtin/pack-objects.c
+++ b/builtin/pack-objects.c
@@ -18,8 +18,8 @@
 #include "refs.h"
 
 #ifndef NO_PTHREADS
-#include "thread-utils.h"
 #include <pthread.h>
+#include "thread-utils.h"
 #endif
 
 static const char pack_usage[] =
@@ -1522,6 +1522,13 @@ static void find_deltas(struct object_entry **list, unsigned *list_size,
 
 #ifndef NO_PTHREADS
 
+static void try_to_free_from_threads(size_t size)
+{
+	read_lock();
+	release_pack_memory(size, -1);
+	read_unlock();
+}
+
 /*
  * The main thread waits on the condition that (at least) one of the workers
  * has stopped working (which is indicated in the .working member of
@@ -1552,14 +1559,16 @@ static pthread_cond_t progress_cond;
  */
 static void init_threaded_search(void)
 {
-	pthread_mutex_init(&read_mutex, NULL);
+	init_recursive_mutex(&read_mutex);
 	pthread_mutex_init(&cache_mutex, NULL);
 	pthread_mutex_init(&progress_mutex, NULL);
 	pthread_cond_init(&progress_cond, NULL);
+	set_try_to_free_routine(try_to_free_from_threads);
 }
 
 static void cleanup_threaded_search(void)
 {
+	set_try_to_free_routine(NULL);
 	pthread_cond_destroy(&progress_cond);
 	pthread_mutex_destroy(&read_mutex);
 	pthread_mutex_destroy(&cache_mutex);
diff --git a/compat/win32/pthread.h b/compat/win32/pthread.h
index c72f100f40..a45f8d66df 100644
--- a/compat/win32/pthread.h
+++ b/compat/win32/pthread.h
@@ -18,11 +18,17 @@
  */
 #define pthread_mutex_t CRITICAL_SECTION
 
-#define pthread_mutex_init(a,b) InitializeCriticalSection((a))
+#define pthread_mutex_init(a,b) (InitializeCriticalSection((a)), 0)
 #define pthread_mutex_destroy(a) DeleteCriticalSection((a))
 #define pthread_mutex_lock EnterCriticalSection
 #define pthread_mutex_unlock LeaveCriticalSection
 
+typedef int pthread_mutexattr_t;
+#define pthread_mutexattr_init(a) (*(a) = 0)
+#define pthread_mutexattr_destroy(a) do {} while (0)
+#define pthread_mutexattr_settype(a, t) 0
+#define PTHREAD_MUTEX_RECURSIVE 0
+
 /*
  * Implement simple condition variable for Windows threads, based on ACE
  * implementation.
diff --git a/git-compat-util.h b/git-compat-util.h
index b96912b5d3..c4f4e15036 100644
--- a/git-compat-util.h
+++ b/git-compat-util.h
@@ -356,6 +356,8 @@ static inline void *gitmempcpy(void *dest, const void *src, size_t n)
 
 extern void release_pack_memory(size_t, int);
 
+extern void set_try_to_free_routine(void (*routine)(size_t));
+
 extern char *xstrdup(const char *str);
 extern void *xmalloc(size_t size);
 extern void *xmallocz(size_t size);
diff --git a/thread-utils.c b/thread-utils.c
index 4f9c829c2d..589f838f82 100644
--- a/thread-utils.c
+++ b/thread-utils.c
@@ -1,4 +1,5 @@
 #include "cache.h"
+#include <pthread.h>
 
 #if defined(hpux) || defined(__hpux) || defined(_hpux)
 #  include <sys/pstat.h>
@@ -43,3 +44,18 @@ int online_cpus(void)
 
 	return 1;
 }
+
+int init_recursive_mutex(pthread_mutex_t *m)
+{
+	pthread_mutexattr_t a;
+	int ret;
+
+	ret = pthread_mutexattr_init(&a);
+	if (!ret) {
+		ret = pthread_mutexattr_settype(&a, PTHREAD_MUTEX_RECURSIVE);
+		if (!ret)
+			ret = pthread_mutex_init(m, &a);
+		pthread_mutexattr_destroy(&a);
+	}
+	return ret;
+}
diff --git a/thread-utils.h b/thread-utils.h
index cce4b77bd6..1727a03333 100644
--- a/thread-utils.h
+++ b/thread-utils.h
@@ -2,5 +2,6 @@
 #define THREAD_COMPAT_H
 
 extern int online_cpus(void);
+extern int init_recursive_mutex(pthread_mutex_t*);
 
 #endif /* THREAD_COMPAT_H */
diff --git a/wrapper.c b/wrapper.c
index 9c71b21242..62edb57338 100644
--- a/wrapper.c
+++ b/wrapper.c
@@ -3,11 +3,23 @@
  */
 #include "cache.h"
 
+static void try_to_free_builtin(size_t size)
+{
+	release_pack_memory(size, -1);
+}
+
+static void (*try_to_free_routine)(size_t size) = try_to_free_builtin;
+
+void set_try_to_free_routine(void (*routine)(size_t))
+{
+	try_to_free_routine = (routine) ? routine : try_to_free_builtin;
+}
+
 char *xstrdup(const char *str)
 {
 	char *ret = strdup(str);
 	if (!ret) {
-		release_pack_memory(strlen(str) + 1, -1);
+		try_to_free_routine(strlen(str) + 1);
 		ret = strdup(str);
 		if (!ret)
 			die("Out of memory, strdup failed");
@@ -21,7 +33,7 @@ void *xmalloc(size_t size)
 	if (!ret && !size)
 		ret = malloc(1);
 	if (!ret) {
-		release_pack_memory(size, -1);
+		try_to_free_routine(size);
 		ret = malloc(size);
 		if (!ret && !size)
 			ret = malloc(1);
@@ -67,7 +79,7 @@ void *xrealloc(void *ptr, size_t size)
 	if (!ret && !size)
 		ret = realloc(ptr, 1);
 	if (!ret) {
-		release_pack_memory(size, -1);
+		try_to_free_routine(size);
 		ret = realloc(ptr, size);
 		if (!ret && !size)
 			ret = realloc(ptr, 1);
@@ -83,7 +95,7 @@ void *xcalloc(size_t nmemb, size_t size)
 	if (!ret && (!nmemb || !size))
 		ret = calloc(1, 1);
 	if (!ret) {
-		release_pack_memory(nmemb * size, -1);
+		try_to_free_routine(nmemb * size);
 		ret = calloc(nmemb, size);
 		if (!ret && (!nmemb || !size))
 			ret = calloc(1, 1);