diff --git a/fast-import.c b/fast-import.c
index 3c035a5..fb4367a 100644
--- a/fast-import.c
+++ b/fast-import.c
@@ -549,11 +549,15 @@ static unsigned int hc_str(const char *s, size_t len)
 	return r;
 }
 
-static void *pool_alloc(size_t len)
+static void *_pool_alloc(size_t len, int zero)
 {
 	struct mem_pool *p;
 	void *r;
 
+	/* round out to a 'uintmax_t' alignment */
+	if (len & (sizeof(uintmax_t) - 1))
+		len += sizeof(uintmax_t) - (len & (sizeof(uintmax_t) - 1));
+
 	for (p = mem_pool; p; p = p->next_pool)
 		if ((p->end - p->next_free >= len))
 			break;
@@ -561,7 +565,8 @@ static void *pool_alloc(size_t len)
 	if (!p) {
 		if (len >= (mem_pool_alloc/2)) {
 			total_allocd += len;
-			return xmalloc(len);
+			r = xmalloc(len);
+			goto out;
 		}
 		total_allocd += sizeof(struct mem_pool) + mem_pool_alloc;
 		p = xmalloc(sizeof(struct mem_pool) + mem_pool_alloc);
@@ -572,19 +577,22 @@ static void *pool_alloc(size_t len)
 	}
 
 	r = p->next_free;
-	/* round out to a 'uintmax_t' alignment */
-	if (len & (sizeof(uintmax_t) - 1))
-		len += sizeof(uintmax_t) - (len & (sizeof(uintmax_t) - 1));
 	p->next_free += len;
+out:
+	if (zero)
+		memset(r, 0, len);
 	return r;
 }
 
+static void *pool_alloc(size_t len)
+{
+	return _pool_alloc(len, 0);
+}
+
 static void *pool_calloc(size_t count, size_t size)
 {
 	size_t len = count * size;
-	void *r = pool_alloc(len);
-	memset(r, 0, len);
-	return r;
+	return _pool_alloc(len, 1);
 }
 
 static char *pool_strdup(const char *s)