diff --git a/src/poetry/core/constraints/generic/constraint.py b/src/poetry/core/constraints/generic/constraint.py
index c64a66c6a..fb4f79913 100644
--- a/src/poetry/core/constraints/generic/constraint.py
+++ b/src/poetry/core/constraints/generic/constraint.py
@@ -123,13 +123,11 @@ def allows_any(self, other: BaseConstraint) -> bool:
 
             return True
 
-        elif isinstance(other, MultiConstraint):
-            return self._operator == "!="
+        if isinstance(other, MultiConstraint):
+            return all(self.allows_any(c) for c in other.constraints)
 
-        elif isinstance(other, UnionConstraint):
-            return self._operator == "!=" and any(
-                self.allows_any(c) for c in other.constraints
-            )
+        if isinstance(other, UnionConstraint):
+            return any(self.allows_any(c) for c in other.constraints)
 
         return other.is_any()
 
diff --git a/tests/constraints/generic/test_constraint.py b/tests/constraints/generic/test_constraint.py
index 73063781e..ad2629168 100644
--- a/tests/constraints/generic/test_constraint.py
+++ b/tests/constraints/generic/test_constraint.py
@@ -265,6 +265,31 @@ def test_allows(
             False,
             False,
         ),
+        # "in" / "not in" with MultiConstraint and UnionConstraint
+        (
+            Constraint("tegra", "in"),
+            MultiConstraint(Constraint("win32", "!="), Constraint("linux", "!=")),
+            True,  # "1.2-tegra" contains "tegra" and is neither "win32" nor "linux"
+            False,
+        ),
+        (
+            Constraint("tegra", "not in"),
+            MultiConstraint(Constraint("win32", "!="), Constraint("linux", "!=")),
+            True,  # "darwin" has no "tegra" and is neither "win32" nor "linux"
+            False,
+        ),
+        (
+            Constraint("tegra", "in"),
+            UnionConstraint(Constraint("1.2-tegra"), Constraint("plain")),
+            True,  # "tegra" is in "1.2-tegra"
+            False,
+        ),
+        (
+            Constraint("tegra", "in"),
+            UnionConstraint(Constraint("plain"), Constraint("other")),
+            False,  # "tegra" is not in "plain" or "other"
+            False,
+        ),
     ],
 )
 def test_allows_any_and_allows_all(