diff --git a/src/ytdl_sub/config/preset.py b/src/ytdl_sub/config/preset.py
index db77412e..4a4554ca 100644
--- a/src/ytdl_sub/config/preset.py
+++ b/src/ytdl_sub/config/preset.py
@@ -203,16 +203,18 @@ class Preset(StrictDictValidator):
 
         # Validate added download option variables here since plugins could subsequently use them
         self.downloader_options.validate_with_variables(
-            source_variables=source_variables, override_variables=self.overrides.keys
+            source_variables=source_variables,
+            override_variables=self.overrides.dict_with_format_strings,
         )
         source_variables.extend(self.downloader_options.added_source_variables())
 
-        for plugin_options in sorted(
-            self.plugins.plugin_options, key=lambda pl_options: pl_options.priority.modify_entry
+        for _, plugin_options in sorted(
+            self.plugins.zipped(), key=lambda pl: pl[0].priority.modify_entry
         ):
             # Validate current plugin using source + added plugin variables
             plugin_options.validate_with_variables(
-                source_variables=source_variables, override_variables=self.overrides.keys
+                source_variables=source_variables,
+                override_variables=self.overrides.dict_with_format_strings,
             )
 
             # Extend existing source variables with ones created from this plugin
diff --git a/src/ytdl_sub/config/preset_options.py b/src/ytdl_sub/config/preset_options.py
index ed96b333..2a67b011 100644
--- a/src/ytdl_sub/config/preset_options.py
+++ b/src/ytdl_sub/config/preset_options.py
@@ -33,7 +33,7 @@ class AddsVariablesMixin(ABC):
         return []
 
     def validate_with_variables(
-        self, source_variables: List[str], override_variables: List[str]
+        self, source_variables: List[str], override_variables: Dict[str, str]
     ) -> None:
         """
         Optional validation after init with the session's source and override variables.
diff --git a/src/ytdl_sub/downloaders/generic/collection.py b/src/ytdl_sub/downloaders/generic/collection.py
index ef42e64b..3488b672 100644
--- a/src/ytdl_sub/downloaders/generic/collection.py
+++ b/src/ytdl_sub/downloaders/generic/collection.py
@@ -13,6 +13,7 @@ from ytdl_sub.entries.entry_parent import EntryParent
 from ytdl_sub.utils.file_handler import FileHandler
 from ytdl_sub.validators.strict_dict_validator import StrictDictValidator
 from ytdl_sub.validators.string_formatter_validators import DictFormatterValidator
+from ytdl_sub.validators.string_formatter_validators import StringFormatterValidator
 from ytdl_sub.validators.validators import ListValidator
 from ytdl_sub.validators.validators import StringValidator
 
@@ -124,19 +125,29 @@ class CollectionDownloadOptions(DownloaderValidator):
         return list(self._urls.list[0].variables.keys())
 
     def validate_with_variables(
-        self, source_variables: List[str], override_variables: List[str]
+        self, source_variables: List[str], override_variables: Dict[str, str]
     ) -> None:
         """
         Ensures new variables added are not existing variables
         """
-        # TODO: Make sure they resolve
-        for added_source_var in self.added_source_variables():
-            if added_source_var in source_variables:
+        for source_var_name in self.added_source_variables():
+            if source_var_name in source_variables:
                 raise self._validation_exception(
-                    f"'{added_source_var}' cannot be used as a variable name because it "
+                    f"'{source_var_name}' cannot be used as a variable name because it "
                     f"is an existing source variable"
                 )
 
+        base_variables = dict(
+            override_variables, **{source_var: "dummy_string" for source_var in source_variables}
+        )
+
+        # Apply formatting to each new source variable, ensure it resolves
+        for collection_url in self.collection_urls.list:
+            for source_var_name, source_var_formatter_str in collection_url.variables.items():
+                _ = StringFormatterValidator(
+                    name=f"{self._name}.{source_var_name}", value=source_var_formatter_str
+                ).apply_formatter(base_variables)
+
 
 class CollectionDownloader(Downloader[CollectionDownloadOptions, Entry]):
     downloader_options_type = CollectionDownloadOptions
diff --git a/src/ytdl_sub/plugins/regex.py b/src/ytdl_sub/plugins/regex.py
index 34070fbd..b818e9da 100644
--- a/src/ytdl_sub/plugins/regex.py
+++ b/src/ytdl_sub/plugins/regex.py
@@ -165,7 +165,7 @@ class RegexOptions(PluginOptions):
         return self._skip_if_match_fails
 
     def validate_with_variables(
-        self, source_variables: List[str], override_variables: List[str]
+        self, source_variables: List[str], override_variables: Dict[str, str]
     ) -> None:
         """
         Ensures each source variable capture group is valid