diff --git a/du6/program.c b/du6/program.c
index 8f08c43..e1c1f81 100644
--- a/du6/program.c
+++ b/du6/program.c
@@ -80,11 +80,11 @@ int run_system(Tree *node) {
         return 0;
     }
 
-    if (strcmp(c,'a') == 0) {
+    if (strcmp(c,"a") == 0) {
 	if (node->left != NULL){
         	return run_system(node->left);
 	}
-    } else if (strcmp(c, 'n') == 0) {
+    } else if (strcmp(c, "n") == 0) {
 	if (node->right != NULL){
         	return run_system(node->right);
 	}