diff --git a/tivars/types/list.py b/tivars/types/list.py
index a39675c..3e6c936 100644
--- a/tivars/types/list.py
+++ b/tivars/types/list.py
@@ -57,8 +57,12 @@ def __init__(self, init=None, *,
 
     def __format__(self, format_spec: str) -> str:
         match format_spec:
-            case "t": return f"{{{','.join(format(entry, 't') for entry in self.list())}}}"
-            case _: return f"[{', '.join(format(entry, format_spec) for entry in self.list())}]"
+            case "":
+                return "[" + ", ".join(format(entry, format_spec) for entry in self.list()) + "]"
+            case "t":
+                return "{" + ",".join(format(entry, 't') for entry in self.list()) + "}"
+            case _:
+                return super().__format__(format_spec)
 
     def __iter__(self) -> Iterator[_E]:
         return iter(self.list())
diff --git a/tivars/types/matrix.py b/tivars/types/matrix.py
index 3911a1c..cd23040 100644
--- a/tivars/types/matrix.py
+++ b/tivars/types/matrix.py
@@ -38,14 +38,15 @@ def __init__(self, init=None, *,
 
     def __format__(self, format_spec: str) -> str:
         match format_spec:
+            case "":
+                inner_sep, outer_sep = ", ", ", "
             case "t":
-                return "[" + \
-                    ''.join(f"[{','.join(format(entry, 't') for entry in row)}]" for row in self.matrix()) \
-                    + "]"
+                inner_sep, outer_sep = ",", ""
             case _:
-                return "[" + \
-                    ', '.join(f"[{', '.join(format(entry, format_spec) for entry in row)}]" for row in self.matrix()) \
-                    + "]"
+                return super().__format__(format_spec)
+
+        return "[" + outer_sep.join(f"[{inner_sep.join(format(entry, format_spec)for entry in row)}]"
+                                    for row in self.matrix()) + "]"
 
     def __iter__(self) -> Iterator[TIReal]:
         for row in self.matrix():
diff --git a/tivars/types/numeric.py b/tivars/types/numeric.py
index 27bf806..8e1f002 100644
--- a/tivars/types/numeric.py
+++ b/tivars/types/numeric.py
@@ -118,9 +118,16 @@ def __float__(self) -> float:
 
     def __format__(self, format_spec: str) -> str:
         match format_spec:
-            case "": return self.string()
-            case "t": return self.string().replace("-", "~")
-            case _: return format(self.decimal(), format_spec)
+            case "":
+                return self.string()
+            case "t":
+                return self.string().replace("-", "~")
+            case _:
+                try:
+                    return format(self.decimal(), format_spec)
+
+                except (TypeError, ValueError):
+                    return super().__format__(format_spec)
 
     def __int__(self) -> int:
         return self.int()
@@ -287,9 +294,16 @@ def __complex__(self):
 
     def __format__(self, format_spec: str) -> str:
         match format_spec:
-            case "": return self.string()
-            case "t": return squash(replacer(self.string(), {"i": "[i]", "-": "~", "~ ": "- "}))
-            case _: return format(self.complex(), format_spec)
+            case "":
+                return self.string()
+            case "t":
+                return squash(replacer(self.string(), {"i": "[i]", "-": "~", "~ ": "- "}))
+            case _:
+                try:
+                    return format(self.complex(), format_spec)
+
+                except (TypeError, ValueError):
+                    return super().__format__(format_spec)
 
     @Section(min_data_length)
     def data(self) -> bytearray:
diff --git a/tivars/var.py b/tivars/var.py
index f595f80..b33f1e9 100644
--- a/tivars/var.py
+++ b/tivars/var.py
@@ -226,6 +226,9 @@ def __eq__(self, other: 'TIEntry') -> bool:
         except AttributeError:
             return False
 
+    def __format__(self, format_spec: str) -> str:
+        raise TypeError(f"unsupported format string passed to {type(self)}.__format__")
+
     def __iter__(self) -> Iterator:
         raise NotImplementedError