diff --git a/main.cpp b/main.cpp
index 8b7eddb82..e317da318 100644
--- a/main.cpp
+++ b/main.cpp
@@ -2041,7 +2041,7 @@ std::pair<int, metadata> read_input(std::vector<source> &sources, char *fname, i
 			vertex_readers.push_back(readers[i].vertexfile);
 			rewind(readers[i].vertexfile);
 		}
-		fqsort(vertex_readers, sizeof(vertex), vertexcmp, vertex_out, memsize / 10, 0);
+		fqsort(vertex_readers, sizeof(vertex), vertexcmp, vertex_out, memsize / 20, 0);
 
 		for (size_t i = 0; i < CPUS; i++) {
 			if (fclose(readers[i].vertexfile) != 0) {
@@ -2107,7 +2107,7 @@ std::pair<int, metadata> read_input(std::vector<source> &sources, char *fname, i
 			rewind(readers[i].nodefile);
 		}
 
-		fqsort(node_readers, sizeof(node), nodecmp, node_out, memsize / 10, 0);
+		fqsort(node_readers, sizeof(node), nodecmp, node_out, memsize / 20, 0);
 
 		for (size_t i = 0; i < CPUS; i++) {
 			if (fclose(readers[i].nodefile) != 0) {
diff --git a/sort.cpp b/sort.cpp
index de75d5e87..467466a5a 100644
--- a/sort.cpp
+++ b/sort.cpp
@@ -10,6 +10,7 @@ void fqsort(std::vector<FILE *> &inputs, size_t width, int (*cmp)(const void *,
 	std::string pivot;
 	FILE *fp1, *fp2;
 	size_t first = 0, second = 0;
+	fprintf(stderr, "using maximum of %zu bytes of memory for sort\n", mem);
 
 	{
 		// read some elements into memory to choose a pivot from