diff --git a/src/ytdl_sub/script/types/map.py b/src/ytdl_sub/script/types/map.py
index 624b6206..60b99b0b 100644
--- a/src/ytdl_sub/script/types/map.py
+++ b/src/ytdl_sub/script/types/map.py
@@ -11,7 +11,7 @@ from ytdl_sub.script.types.resolvable import Resolvable
 from ytdl_sub.script.types.resolvable import ResolvableToJson
 from ytdl_sub.script.types.variable import Variable
 from ytdl_sub.script.types.variable_dependency import VariableDependency
-from ytdl_sub.utils.exceptions import StringFormattingException
+from ytdl_sub.script.utils.exceptions import KeyNotHashableRuntimeException
 
 
 @dataclass(frozen=True)
@@ -42,7 +42,9 @@ class UnresolvedMap(Map, VariableDependency, AnyArgument):
                 arg=key, resolved_variables=resolved_variables, custom_functions=custom_functions
             )
             if not isinstance(resolved_key, Hashable):
-                raise StringFormattingException("key is not hashable")
+                raise KeyNotHashableRuntimeException(
+                    f"Tried to use {resolved_key.type_name()} as a Map key, but it is not hashable."
+                )
 
             output[resolved_key] = self._resolve_argument_type(
                 arg=value, resolved_variables=resolved_variables, custom_functions=custom_functions
diff --git a/src/ytdl_sub/script/types/variable_dependency.py b/src/ytdl_sub/script/types/variable_dependency.py
index c0182bb7..a40744fc 100644
--- a/src/ytdl_sub/script/types/variable_dependency.py
+++ b/src/ytdl_sub/script/types/variable_dependency.py
@@ -12,7 +12,6 @@ from ytdl_sub.script.types.resolvable import Resolvable
 from ytdl_sub.script.types.variable import FunctionArgument
 from ytdl_sub.script.types.variable import Variable
 from ytdl_sub.script.utils.exceptions import UNREACHABLE
-from ytdl_sub.utils.exceptions import StringFormattingException
 
 
 @dataclass(frozen=True)
@@ -78,7 +77,8 @@ class VariableDependency(ABC):
             return arg
         if isinstance(arg, Variable):
             if arg not in resolved_variables:
-                raise StringFormattingException("should never reach@")
+                # All variables should exist and be resolved at this point
+                raise UNREACHABLE
             return resolved_variables[arg]
         if isinstance(arg, VariableDependency):
             return arg.resolve(
diff --git a/src/ytdl_sub/script/utils/exceptions.py b/src/ytdl_sub/script/utils/exceptions.py
index dc9e63b6..762a0a56 100644
--- a/src/ytdl_sub/script/utils/exceptions.py
+++ b/src/ytdl_sub/script/utils/exceptions.py
@@ -43,10 +43,18 @@ class CycleDetected(UserException):
     """A cycle exists within a user's script"""
 
 
-class FunctionRuntimeException(ValueError):
+class RuntimeException(ValueError, ABC):
+    """Exception thrown at runtime during resolution"""
+
+
+class FunctionRuntimeException(RuntimeException):
     """Exception thrown when a ytdl-sub function has an error occur at runtime"""
 
 
+class KeyNotHashableRuntimeException(RuntimeException):
+    """Map tried to use a non-hashable key at runtime"""
+
+
 class UserThrownRuntimeError(ValidationException):
     """An error explicitly thrown by the user via a function"""
 
diff --git a/tests/unit/script/types/test_map.py b/tests/unit/script/types/test_map.py
index 51159760..36603a77 100644
--- a/tests/unit/script/types/test_map.py
+++ b/tests/unit/script/types/test_map.py
@@ -15,6 +15,7 @@ from ytdl_sub.script.types.resolvable import Boolean
 from ytdl_sub.script.types.resolvable import Float
 from ytdl_sub.script.types.resolvable import String
 from ytdl_sub.script.utils.exceptions import InvalidSyntaxException
+from ytdl_sub.script.utils.exceptions import KeyNotHashableRuntimeException
 
 
 class TestMap:
@@ -159,3 +160,26 @@ class TestMap:
     def test_map_key_not_hashable(self, value: str):
         with pytest.raises(InvalidSyntaxException, match=re.escape(str(MAP_KEY_NOT_HASHABLE))):
             Script({"map": value}).resolve()
+
+    def test_map_key_is_hashable_variable(self):
+        assert Script(
+            {
+                "map": "{{key_variable : 'value' }}",
+                "key_variable": "hashable",
+            }
+        ).resolve() == {
+            "key_variable": String("hashable"),
+            "map": ResolvedMap({String("hashable"): String("value")}),
+        }
+
+    def test_map_key_is_non_hashable_variable(self):
+        with pytest.raises(
+            KeyNotHashableRuntimeException,
+            match=re.escape("Tried to use Array as a Map key, but it is not hashable."),
+        ):
+            Script(
+                {
+                    "map": "{{key_variable : 'value' }}",
+                    "key_variable": "{['non-hashable']}",
+                }
+            ).resolve()