diff --git a/src/outlines/types/dsl.py b/src/outlines/types/dsl.py
index 5949a67a4..19504c392 100644
--- a/src/outlines/types/dsl.py
+++ b/src/outlines/types/dsl.py
@@ -574,6 +574,10 @@ class QuantifyExact(Term):
     term: Term
     count: int
 
+    def __post_init__(self):
+        if self.count < 0:
+            raise ValueError("QuantifyExact: `count` must be a non-negative integer.")
+
     def _display_node(self) -> str:
         return f"Quantify({{{self.count}}})"
 
@@ -589,6 +593,12 @@ class QuantifyMinimum(Term):
     term: Term
     min_count: int
 
+    def __post_init__(self):
+        if self.min_count < 0:
+            raise ValueError(
+                "QuantifyMinimum: `min_count` must be a non-negative integer."
+            )
+
     def _display_node(self) -> str:
         return f"Quantify({{{self.min_count},}})"
 
@@ -606,6 +616,12 @@ class QuantifyMaximum(Term):
     term: Term
     max_count: int
 
+    def __post_init__(self):
+        if self.max_count < 0:
+            raise ValueError(
+                "QuantifyMaximum: `max_count` must be a non-negative integer."
+            )
+
     def _display_node(self) -> str:
         return f"Quantify({{,{self.max_count}}})"
 
@@ -625,6 +641,10 @@ class QuantifyBetween(Term):
     max_count: int
 
     def __post_init__(self):
+        if self.min_count < 0:
+            raise ValueError(
+                "QuantifyBetween: `min_count` must be a non-negative integer."
+            )
         if self.min_count > self.max_count:
             raise ValueError(
                 "QuantifyBetween: `max_count` must be greater than `min_count`."
diff --git a/tests/types/test_dsl.py b/tests/types/test_dsl.py
index f827d9386..94938325c 100644
--- a/tests/types/test_dsl.py
+++ b/tests/types/test_dsl.py
@@ -138,6 +138,15 @@ def test_dsl_init():
     assert repr(maximum) == "QuantifyMaximum(term=String(value='test'), max_count=3)"
     assert maximum.display_ascii_tree() == "└── Quantify({,3})\n    └── String('test')\n"
 
+    with pytest.raises(ValueError, match="`count` must be a non-negative integer"):
+        QuantifyExact(string, -1)
+
+    with pytest.raises(ValueError, match="`min_count` must be a non-negative integer"):
+        QuantifyMinimum(string, -1)
+
+    with pytest.raises(ValueError, match="`max_count` must be a non-negative integer"):
+        QuantifyMaximum(string, -1)
+
     between = QuantifyBetween(string, 1, 3)
     assert between.term == string
     assert between.min_count == 1
@@ -153,6 +162,9 @@ def test_dsl_init():
     ):
         QuantifyBetween(string, 3, 1)
 
+    with pytest.raises(ValueError, match="`min_count` must be a non-negative integer"):
+        QuantifyBetween(string, -2, -1)
+
 
 def test_dsl_term_methods():
     a = String("a")