diff --git a/src/xdiff/xpatience.c b/src/xdiff/xpatience.c
index f78c897..894a1ba 100644
--- a/src/xdiff/xpatience.c
+++ b/src/xdiff/xpatience.c
@@ -69,7 +69,6 @@
 	} *entries, *first, *last;
 	/* were common records found? */
 	unsigned long has_matches;
-	mmfile_t *file1, *file2;
 	xdfenv_t *env;
 	xpparam_t const *xpp;
 };
@@ -139,23 +138,17 @@
  *
  * It is assumed that env has been prepared using xdl_prepare().
  */
-static int fill_hashmap(mmfile_t *file1, mmfile_t *file2,
-		xpparam_t const *xpp, xdfenv_t *env,
+static int fill_hashmap(xpparam_t const *xpp, xdfenv_t *env,
 		struct hashmap *result,
 		int line1, int count1, int line2, int count2)
 {
-	result->file1 = file1;
-	result->file2 = file2;
 	result->xpp = xpp;
 	result->env = env;
 
 	/* We know exactly how large we want the hash map */
 	result->alloc = count1 * 2;
-	result->entries = (struct entry *)
-		xdl_malloc(result->alloc * sizeof(struct entry));
-	if (!result->entries)
+	if (!XDL_CALLOC_ARRAY(result->entries, result->alloc))
 		return -1;
-	memset(result->entries, 0, result->alloc * sizeof(struct entry));
 
 	/* First, fill with entries from the first file */
 	while (count1--)
@@ -198,9 +191,9 @@
  * item per sequence length: the sequence with the smallest last
  * element (in terms of line2).
  */
-static struct entry *find_longest_common_sequence(struct hashmap *map)
+static int find_longest_common_sequence(struct hashmap *map, struct entry **res)
 {
-	struct entry **sequence = xdl_malloc(map->nr * sizeof(struct entry *));
+	struct entry **sequence;
 	int longest = 0, i;
 	struct entry *entry;
 
@@ -211,9 +204,8 @@
 	 */
 	int anchor_i = -1;
 
-	// Added to silence Coverity.
-	if (sequence == NULL)
-		return map->first;
+	if (!XDL_ALLOC_ARRAY(sequence, map->nr))
+		return -1;
 
 	for (entry = map->first; entry; entry = entry->next) {
 		if (!entry->line2 || entry->line2 == NON_UNIQUE)
@@ -234,8 +226,9 @@
 
 	/* No common unique lines were found */
 	if (!longest) {
+		*res = NULL;
 		xdl_free(sequence);
-		return NULL;
+		return 0;
 	}
 
 	/* Iterate starting at the last element, adjusting the "next" members */
@@ -245,8 +238,9 @@
 		entry->previous->next = entry;
 		entry = entry->previous;
 	}
+	*res = entry;
 	xdl_free(sequence);
-	return entry;
+	return 0;
 }
 
 static int match(struct hashmap *map, int line1, int line2)
@@ -256,8 +250,7 @@
 	return record1->ha == record2->ha;
 }
 
-static int patience_diff(mmfile_t *file1, mmfile_t *file2,
-		xpparam_t const *xpp, xdfenv_t *env,
+static int patience_diff(xpparam_t const *xpp, xdfenv_t *env,
 		int line1, int count1, int line2, int count2);
 
 static int walk_common_sequence(struct hashmap *map, struct entry *first,
@@ -288,8 +281,7 @@
 
 		/* Recurse */
 		if (next1 > line1 || next2 > line2) {
-			if (patience_diff(map->file1, map->file2,
-					map->xpp, map->env,
+			if (patience_diff(map->xpp, map->env,
 					line1, next1 - line1,
 					line2, next2 - line2))
 				return -1;
@@ -328,8 +320,7 @@
  *
  * This function assumes that env was prepared with xdl_prepare_env().
  */
-static int patience_diff(mmfile_t *file1, mmfile_t *file2,
-		xpparam_t const *xpp, xdfenv_t *env,
+static int patience_diff(xpparam_t const *xpp, xdfenv_t *env,
 		int line1, int count1, int line2, int count2)
 {
 	struct hashmap map;
@@ -348,7 +339,7 @@
 	}
 
 	memset(&map, 0, sizeof(map));
-	if (fill_hashmap(file1, file2, xpp, env, &map,
+	if (fill_hashmap(xpp, env, &map,
 			line1, count1, line2, count2))
 		return -1;
 
@@ -362,25 +353,21 @@
 		return 0;
 	}
 
-	first = find_longest_common_sequence(&map);
+	result = find_longest_common_sequence(&map, &first);
+	if (result)
+		goto out;
 	if (first)
 		result = walk_common_sequence(&map, first,
 			line1, count1, line2, count2);
 	else
 		result = fall_back_to_classic_diff(&map,
 			line1, count1, line2, count2);
-
+ out:
 	xdl_free(map.entries);
 	return result;
 }
 
-int xdl_do_patience_diff(mmfile_t *file1, mmfile_t *file2,
-		xpparam_t const *xpp, xdfenv_t *env)
+int xdl_do_patience_diff(xpparam_t const *xpp, xdfenv_t *env)
 {
-	if (xdl_prepare_env(file1, file2, xpp, env) < 0)
-		return -1;
-
-	/* environment is cleaned up in xdl_diff() */
-	return patience_diff(file1, file2, xpp, env,
-			1, env->xdf1.nrec, 1, env->xdf2.nrec);
+	return patience_diff(xpp, env, 1, env->xdf1.nrec, 1, env->xdf2.nrec);
 }