diff --git a/src/tup/file.c b/src/tup/file.c
index c14f551b4..fe7047f75 100644
--- a/src/tup/file.c
+++ b/src/tup/file.c
@@ -46,7 +46,12 @@ static int add_parser_files_locked(struct file_info *finfo,
 				   struct tent_entries *root, tupid_t vardt,
 				   int full_deps);
 
-static _Thread_local struct mempool pool = MEMPOOL_INITIALIZER(struct file_entry);
+// Note it will not work with per-thread pools here because all the allocation
+// is done by the fuse server thread while all the free is done by the
+// worker threads. Thus the free'd memory cannot be reused by the fuse server 
+// thread so the memory usage just keeps growing.
+static struct mempool pool = MEMPOOL_INITIALIZER(struct file_entry);
+static pthread_mutex_t pool_lock = PTHREAD_MUTEX_INITIALIZER;
 
 int init_file_info(struct file_info *info, int do_unlink)
 {
@@ -549,7 +554,9 @@ static struct file_entry *new_entry(const char *filename)
 {
 	struct file_entry *fent;
 
+	pthread_mutex_lock(&pool_lock);
 	fent = mempool_alloc(&pool);
+	pthread_mutex_unlock(&pool_lock);
 	if(!fent) {
 		return NULL;
 	}
@@ -557,7 +564,9 @@ static struct file_entry *new_entry(const char *filename)
 	fent->filename = strdup(filename);
 	if(!fent->filename) {
 		perror("strdup");
+		pthread_mutex_lock(&pool_lock);
 		mempool_free(&pool, fent);
+		pthread_mutex_unlock(&pool_lock);
 		return NULL;
 	}
 	return fent;
@@ -567,7 +576,9 @@ void del_file_entry(struct file_entry_head *head, struct file_entry *fent)
 {
 	TAILQ_REMOVE(head, fent, list);
 	free(fent->filename);
+	pthread_mutex_lock(&pool_lock);
 	mempool_free(&pool, fent);
+	pthread_mutex_unlock(&pool_lock);
 }
 
 int handle_rename(const char *from, const char *to, struct file_info *info)
diff --git a/src/tup/mempool.c b/src/tup/mempool.c
index 5c7f01ab9..a59556a6d 100644
--- a/src/tup/mempool.c
+++ b/src/tup/mempool.c
@@ -48,7 +48,7 @@ void *mempool_alloc(struct mempool *pool)
 		 * memory allocated here is not freed until the program quits.
 		 */
 		if(pool->item_size < sizeof(struct mementry)) {
-			fprintf(stderr, "tup internal error: mempool item size too small: %i\n", pool->item_size);
+			fprintf(stderr, "tup internal error: mempool item size too small: %zu\n", pool->item_size);
 			return NULL;
 		}
 
@@ -79,7 +79,7 @@ void *mempool_alloc(struct mempool *pool)
 	 * next item from the pool's memory.
 	 */
 	if(((uintptr_t)pool->mem & (pool->alignment-1)) != 0) {
-		fprintf(stderr, "tup internal error: memory address in mempool (%p) not aligned to %u bytes.\n", pool->mem, pool->alignment);
+		fprintf(stderr, "tup internal error: memory address in mempool (%p) not aligned to %zu bytes.\n", pool->mem, pool->alignment);
 		return NULL;
 	}
 	ret = (void*)pool->mem;
diff --git a/src/tup/mempool.h b/src/tup/mempool.h
index 50f88f256..0bcbcf734 100644
--- a/src/tup/mempool.h
+++ b/src/tup/mempool.h
@@ -23,6 +23,8 @@
 
 #include "bsd/queue.h"
 
+#include <stddef.h>
+
 struct mementry {
 	SLIST_ENTRY(mementry) list;
 };
@@ -30,10 +32,10 @@ SLIST_HEAD(mementry_head, mementry);
 
 struct mempool {
 	struct mementry_head free_list;
-	unsigned int item_size;
-	unsigned int next_alloc_size;
-	unsigned int alignment;
-	int free_count;
+	size_t item_size;
+	size_t next_alloc_size;
+	size_t alignment;
+	size_t free_count;
 	char *mem;
 };
 TAILQ_HEAD(mempool_head, mempool);