diff --git a/cpath/src/cpath.c b/cpath/src/cpath.c
index 50531f6..e6c725d 100644
--- a/cpath/src/cpath.c
+++ b/cpath/src/cpath.c
@@ -32,7 +32,10 @@ void dirup(char *dst, u64 levels, const char *path) {
   u64 end_index = 0;
   u64 sep_count = 0;
 
-  u64 length = strlen(path);
+  u64 full_length;
+  u64 length;
+  length = full_length = strlen(path);
+
   if (path[length - 1] == path_sep) {
     --length;
   }
@@ -52,7 +55,13 @@ void dirup(char *dst, u64 levels, const char *path) {
     end_index = 0;
   }
 
-  strncpy(dst, path, end_index);
+  if (dst == path) {
+    memset(&dst[end_index], 0, full_length - end_index);
+  } else {
+    u64 dst_length = strlen(dst);
+    memset(dst, 0, dst_length);
+    strncpy(dst, path, end_index);
+  }
 }
 
 void join_root_and_leaf(const char *root, const char *leaf, char *dst) {