diff --git a/PFERD/crawler.py b/PFERD/crawler.py
index f506294..48dfcb4 100644
--- a/PFERD/crawler.py
+++ b/PFERD/crawler.py
@@ -122,7 +122,12 @@ class CrawlerSection(Section):
             return Redownload.ALWAYS
         elif value == "always-smart":
             return Redownload.ALWAYS_SMART
-        self.invalid_value("redownload", value)
+
+        self.invalid_value(
+            "redownload",
+            value,
+            "Must be 'never', 'never-smart', 'always' or 'always-smart'"
+        )
 
     def on_conflict(self) -> OnConflict:
         value = self.s.get("on_conflict", "prompt")
@@ -134,7 +139,12 @@ class CrawlerSection(Section):
             return OnConflict.REMOTE_FIRST
         elif value == "no-delete":
             return OnConflict.NO_DELETE
-        self.invalid_value("on_conflict", value)
+
+        self.invalid_value(
+            "on_conflict",
+            value,
+            "Must be 'prompt', 'local-first', 'remote-first' or 'no-delete'",
+        )
 
     def transform(self) -> str:
         return self.s.get("transform", "")
@@ -167,7 +177,7 @@ class CrawlerSection(Section):
             self.missing_value("auth")
         auth = authenticators.get(f"auth:{value}")
         if auth is None:
-            self.invalid_value("auth", value)
+            self.invalid_value("auth", value, "No such auth section exists")
         return auth
 
 
diff --git a/PFERD/crawlers/local.py b/PFERD/crawlers/local.py
index 1677ff0..07e6133 100644
--- a/PFERD/crawlers/local.py
+++ b/PFERD/crawlers/local.py
@@ -19,19 +19,22 @@ class LocalCrawlerSection(CrawlerSection):
     def crawl_delay(self) -> Optional[float]:
         value = self.s.getfloat("crawl_delay")
         if value <= 0:
-            self.invalid_value("crawl_delay", value)
+            self.invalid_value("crawl_delay", value,
+                               "Must be greater than 0")
         return value
 
     def download_delay(self) -> Optional[float]:
         value = self.s.getfloat("download_delay")
         if value <= 0:
-            self.invalid_value("download_delay", value)
+            self.invalid_value("download_delay", value,
+                               "Must be greater than 0")
         return value
 
     def download_speed(self) -> Optional[int]:
         value = self.s.getint("download_speed")
         if value <= 0:
-            self.invalid_value("download_speed", value)
+            self.invalid_value("download_speed", value,
+                               "Must be greater than 0")
         return value