diff --git a/src/utils/fileUtilities.c b/src/utils/fileUtilities.c
index 5a342f7..a75ee5d 100644
--- a/src/utils/fileUtilities.c
+++ b/src/utils/fileUtilities.c
@@ -48,7 +48,7 @@ void openNextFile() {
   //We need to transfer carry if necessary (e.g. .z09 to .z10), otherwise just increase last digit
   if (file.name[fileNameLength - 1] == '9') {
     file.name[fileNameLength - 2] += 1;
-    file.name[fileNameLength - 1] = 0;
+    file.name[fileNameLength - 1] = '0';
   } else {
     file.name[fileNameLength - 1] += 1;
   }