1 files changed, 7 insertions, 5 deletions
diff --git a/src/matrix.c b/src/matrix.c
index a23aad4..953d50f 100644
--- a/src/matrix.c
+++ b/src/matrix.c
@@ -1,5 +1,6 @@
 #include "lizfcm.h"
 #include <assert.h>
+#include <string.h>
 #include <stdio.h>
 
 void put_identity_diagonal(Matrix_double *m) {
@@ -69,14 +70,15 @@ void free_matrix(Matrix_double *m) {
 }
 
 void format_matrix_into(Matrix_double *m, char *s) {
-  sprintf(s, "");
   if (m->rows == 0)
-    sprintf(s, "empty");
+    strcpy(s, "empty");
 
   for (size_t y = 0; y < m->rows; ++y) {
-    char *row_s = malloc(sizeof(char) * 256);
+    char row_s[256];
+    strcpy(row_s, "");
+
     format_vector_into(m->data[y], row_s);
-    sprintf(s, "%s %s \n", s, row_s);
-    free(row_s);
+    strcat(s, row_s);
   }
+  strcat(s, "\n");
 }