diff --git a/constructor/utils.py b/constructor/utils.py
index 277c2cead..4b2c6352a 100644
--- a/constructor/utils.py
+++ b/constructor/utils.py
@@ -178,6 +178,11 @@ def ensure_transmuted_ext(info, url):
 
 def get_final_url(info, url):
     mapping = info.get('channels_remap', [])
+    if not url.lower().endswith((".tar.bz2", ".conda", "/")):
+        url += "/"
+        added_slash = True
+    else:
+        added_slash = False
     for entry in mapping:
         src = entry['src']
         dst = entry['dest']
@@ -186,7 +191,6 @@ def get_final_url(info, url):
             srcs = tuple(
                 dict.fromkeys(
                     [
-                        src,
                         src.replace("http://", "https://"),
                         src.replace("https://", "http://")
                     ]
@@ -195,11 +199,14 @@ def get_final_url(info, url):
         else:
             srcs = (src,)
         if url.startswith(srcs):
+            new_url = url
             for src in srcs:
-                new_url = url.replace(src, dst)
+                new_url = new_url.replace(src, dst)
             if url.endswith(".tar.bz2"):
                 logger.warning("You need to make the package %s available "
                                "at %s", url.rsplit('/', 1)[1], new_url)
+            if added_slash:
+                new_url = new_url[:-1]
             return new_url
     return url