diff --git a/src/poetry/core/packages/dependency.py b/src/poetry/core/packages/dependency.py
index 083a33392..229ddc313 100644
--- a/src/poetry/core/packages/dependency.py
+++ b/src/poetry/core/packages/dependency.py
@@ -56,9 +56,9 @@ def __init__(
         )
 
         self._constraint = None
+        self._pretty_constraint = None
         self.set_constraint(constraint=constraint)
 
-        self._pretty_constraint = str(constraint)
         self._optional = optional
 
         if not groups:
@@ -109,6 +109,7 @@ def set_constraint(self, constraint: Union[str, "VersionTypes"]) -> None:
                 self._constraint = constraint
         except ValueError:
             self._constraint = parse_constraint("*")
+        self._pretty_constraint = str(constraint)
 
     @property
     def pretty_constraint(self) -> str:
diff --git a/tests/packages/test_dependency.py b/tests/packages/test_dependency.py
index 4c4d2154f..34429a68f 100644
--- a/tests/packages/test_dependency.py
+++ b/tests/packages/test_dependency.py
@@ -250,6 +250,13 @@ def test_dependency_string_representation(
     assert str(dependency) == expected
 
 
+def test_set_constraint_sets_pretty_constraint():
+    dependency = Dependency("A", "^1.0")
+    assert dependency.pretty_constraint == "^1.0"
+    dependency.set_constraint("^2.0")
+    assert dependency.pretty_constraint == "^2.0"
+
+
 def test_with_constraint():
     dependency = Dependency(
         "foo",