diff --git a/ir/normalize.go b/ir/normalize.go
index 8edddac2..aeddf102 100644
--- a/ir/normalize.go
+++ b/ir/normalize.go
@@ -819,28 +819,7 @@ func normalizeExpressionParentheses(expr string) string {
 		expr = fmt.Sprintf("(%s)", expr)
 	}
 
-	// Step 2: Remove unnecessary parentheses around function calls within the expression
-	// Specifically targets patterns like (function_name(...)) -> function_name(...)
-	// This pattern looks for:
-	// \( - opening parenthesis
-	// ([a-zA-Z_][a-zA-Z0-9_]*) - function name (captured)
-	// \( - opening parenthesis for function call
-	// ([^)]*) - function arguments (captured, non-greedy to avoid matching nested parens)
-	// \) - closing parenthesis for function call
-	// \) - closing parenthesis around the whole function
-	functionParensRegex := regexp.MustCompile(`\(([a-zA-Z_][a-zA-Z0-9_]*\([^)]*\))\)`)
-
-	// Replace (function(...)) with function(...)
-	// Keep applying until no more matches to handle nested cases
-	for {
-		original := expr
-		expr = functionParensRegex.ReplaceAllString(expr, "$1")
-		if expr == original {
-			break
-		}
-	}
-
-	// Step 3: Normalize redundant type casts in function arguments
+	// Step 2: Normalize redundant type casts in function arguments
 	// Pattern: 'text'::text -> 'text' (removing redundant text cast from literals)
 	// IMPORTANT: Do NOT match when followed by [] (array cast is semantically significant)
 	// e.g., '{nested,key}'::text[] must be preserved as-is
diff --git a/ir/normalize_test.go b/ir/normalize_test.go
index 5eb31386..f7510387 100644
--- a/ir/normalize_test.go
+++ b/ir/normalize_test.go
@@ -321,6 +321,75 @@ func TestStripSchemaFromReturnType(t *testing.T) {
 	}
 }
 
+func TestNormalizeExpressionParentheses(t *testing.T) {
+	tests := []struct {
+		name     string
+		input    string
+		expected string
+	}{
+		{
+			name:     "simple expression gets wrapped",
+			input:    "tenant_id = 1",
+			expected: "(tenant_id = 1)",
+		},
+		{
+			name:     "already parenthesized",
+			input:    "(tenant_id = 1)",
+			expected: "(tenant_id = 1)",
+		},
+		{
+			name:     "nested function call preserved",
+			input:    "(id IN ( SELECT unnest(get_user_assigned_projects()) AS unnest))",
+			expected: "(id IN ( SELECT unnest(get_user_assigned_projects()) AS unnest))",
+		},
+		{
+			name:     "simple function call preserved",
+			input:    "(has_scope('admin'))",
+			expected: "(has_scope('admin'))",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			result := normalizeExpressionParentheses(tt.input)
+			if result != tt.expected {
+				t.Errorf("normalizeExpressionParentheses(%q) = %q, want %q", tt.input, result, tt.expected)
+			}
+		})
+	}
+}
+
+func TestNormalizePolicyExpression(t *testing.T) {
+	tests := []struct {
+		name        string
+		expr        string
+		tableSchema string
+		expected    string
+	}{
+		{
+			name:        "nested function call in policy expression",
+			expr:        "(id IN ( SELECT unnest(get_user_assigned_projects()) AS unnest))",
+			tableSchema: "public",
+			expected:    "(id IN ( SELECT unnest(get_user_assigned_projects()) AS unnest))",
+		},
+		{
+			name:        "schema-qualified nested function call",
+			expr:        "(id IN ( SELECT unnest(public.get_user_assigned_projects()) AS unnest))",
+			tableSchema: "public",
+			expected:    "(id IN ( SELECT unnest(get_user_assigned_projects()) AS unnest))",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			result := normalizePolicyExpression(tt.expr, tt.tableSchema)
+			if result != tt.expected {
+				t.Errorf("normalizePolicyExpression(%q, %q) = %q, want %q", tt.expr, tt.tableSchema, result, tt.expected)
+			}
+		})
+	}
+}
+
 func TestNormalizeCheckClause(t *testing.T) {
 	tests := []struct {
 		name     string
diff --git a/testdata/diff/create_policy/add_policy/diff.sql b/testdata/diff/create_policy/add_policy/diff.sql
index f3227297..e5545017 100644
--- a/testdata/diff/create_policy/add_policy/diff.sql
+++ b/testdata/diff/create_policy/add_policy/diff.sql
@@ -1,7 +1,7 @@
 ALTER TABLE orders ENABLE ROW LEVEL SECURITY;
 CREATE POLICY orders_user_access ON orders FOR SELECT TO PUBLIC USING (user_id IN ( SELECT users.id FROM users));
-CREATE POLICY "UserPolicy" ON users TO PUBLIC USING (tenant_id = current_setting('app.current_tenant')::integer);
+CREATE POLICY "UserPolicy" ON users TO PUBLIC USING (tenant_id = (current_setting('app.current_tenant'))::integer);
 CREATE POLICY admin_only ON users FOR DELETE TO PUBLIC USING (is_admin());
 CREATE POLICY "my-policy" ON users FOR INSERT TO PUBLIC WITH CHECK ((role)::text = 'user');
 CREATE POLICY "select" ON users FOR SELECT TO PUBLIC USING (true);
-CREATE POLICY user_tenant_isolation ON users FOR UPDATE TO PUBLIC USING (tenant_id = current_setting('app.current_tenant')::integer);
+CREATE POLICY user_tenant_isolation ON users FOR UPDATE TO PUBLIC USING (tenant_id = (current_setting('app.current_tenant'))::integer);
diff --git a/testdata/diff/create_policy/add_policy/plan.json b/testdata/diff/create_policy/add_policy/plan.json
index e7c27d82..1a4bc12e 100644
--- a/testdata/diff/create_policy/add_policy/plan.json
+++ b/testdata/diff/create_policy/add_policy/plan.json
@@ -21,7 +21,7 @@
           "path": "public.orders.orders_user_access"
         },
         {
-          "sql": "CREATE POLICY \"UserPolicy\" ON users TO PUBLIC USING (tenant_id = current_setting('app.current_tenant')::integer);",
+          "sql": "CREATE POLICY \"UserPolicy\" ON users TO PUBLIC USING (tenant_id = (current_setting('app.current_tenant'))::integer);",
           "type": "table.policy",
           "operation": "create",
           "path": "public.users.UserPolicy"
@@ -45,7 +45,7 @@
           "path": "public.users.select"
         },
         {
-          "sql": "CREATE POLICY user_tenant_isolation ON users FOR UPDATE TO PUBLIC USING (tenant_id = current_setting('app.current_tenant')::integer);",
+          "sql": "CREATE POLICY user_tenant_isolation ON users FOR UPDATE TO PUBLIC USING (tenant_id = (current_setting('app.current_tenant'))::integer);",
           "type": "table.policy",
           "operation": "create",
           "path": "public.users.user_tenant_isolation"
diff --git a/testdata/diff/create_policy/add_policy/plan.sql b/testdata/diff/create_policy/add_policy/plan.sql
index e054fda1..7f95e587 100644
--- a/testdata/diff/create_policy/add_policy/plan.sql
+++ b/testdata/diff/create_policy/add_policy/plan.sql
@@ -2,7 +2,7 @@ ALTER TABLE orders ENABLE ROW LEVEL SECURITY;
 
 CREATE POLICY orders_user_access ON orders FOR SELECT TO PUBLIC USING (user_id IN ( SELECT users.id FROM users));
 
-CREATE POLICY "UserPolicy" ON users TO PUBLIC USING (tenant_id = current_setting('app.current_tenant')::integer);
+CREATE POLICY "UserPolicy" ON users TO PUBLIC USING (tenant_id = (current_setting('app.current_tenant'))::integer);
 
 CREATE POLICY admin_only ON users FOR DELETE TO PUBLIC USING (is_admin());
 
@@ -10,4 +10,4 @@ CREATE POLICY "my-policy" ON users FOR INSERT TO PUBLIC WITH CHECK ((role)::text
 
 CREATE POLICY "select" ON users FOR SELECT TO PUBLIC USING (true);
 
-CREATE POLICY user_tenant_isolation ON users FOR UPDATE TO PUBLIC USING (tenant_id = current_setting('app.current_tenant')::integer);
+CREATE POLICY user_tenant_isolation ON users FOR UPDATE TO PUBLIC USING (tenant_id = (current_setting('app.current_tenant'))::integer);
diff --git a/testdata/diff/create_policy/add_policy/plan.txt b/testdata/diff/create_policy/add_policy/plan.txt
index 4e760a23..59f606d2 100644
--- a/testdata/diff/create_policy/add_policy/plan.txt
+++ b/testdata/diff/create_policy/add_policy/plan.txt
@@ -21,7 +21,7 @@ ALTER TABLE orders ENABLE ROW LEVEL SECURITY;
 
 CREATE POLICY orders_user_access ON orders FOR SELECT TO PUBLIC USING (user_id IN ( SELECT users.id FROM users));
 
-CREATE POLICY "UserPolicy" ON users TO PUBLIC USING (tenant_id = current_setting('app.current_tenant')::integer);
+CREATE POLICY "UserPolicy" ON users TO PUBLIC USING (tenant_id = (current_setting('app.current_tenant'))::integer);
 
 CREATE POLICY admin_only ON users FOR DELETE TO PUBLIC USING (is_admin());
 
@@ -29,4 +29,4 @@ CREATE POLICY "my-policy" ON users FOR INSERT TO PUBLIC WITH CHECK ((role)::text
 
 CREATE POLICY "select" ON users FOR SELECT TO PUBLIC USING (true);
 
-CREATE POLICY user_tenant_isolation ON users FOR UPDATE TO PUBLIC USING (tenant_id = current_setting('app.current_tenant')::integer);
+CREATE POLICY user_tenant_isolation ON users FOR UPDATE TO PUBLIC USING (tenant_id = (current_setting('app.current_tenant'))::integer);
diff --git a/testdata/diff/create_policy/alter_policy_roles/plan.json b/testdata/diff/create_policy/alter_policy_roles/plan.json
index cc303b13..c779f988 100644
--- a/testdata/diff/create_policy/alter_policy_roles/plan.json
+++ b/testdata/diff/create_policy/alter_policy_roles/plan.json
@@ -3,7 +3,7 @@
   "pgschema_version": "1.8.0",
   "created_at": "1970-01-01T00:00:00Z",
   "source_fingerprint": {
-    "hash": "a24989791c9ba13d2d21f70cd0405e0e509c55341872b552ab87a0c79d238ddd"
+    "hash": "a5fcd005530df97b095b020e1a8c2fb12333baf056c3a2318bc34f2157893877"
   },
   "groups": [
     {
diff --git a/testdata/diff/create_policy/alter_policy_using/plan.json b/testdata/diff/create_policy/alter_policy_using/plan.json
index 824616c4..9571281c 100644
--- a/testdata/diff/create_policy/alter_policy_using/plan.json
+++ b/testdata/diff/create_policy/alter_policy_using/plan.json
@@ -3,7 +3,7 @@
   "pgschema_version": "1.8.0",
   "created_at": "1970-01-01T00:00:00Z",
   "source_fingerprint": {
-    "hash": "e7aac12e5d350ee9d014b756c838017ddd0c17180b7baa33300f4a773c4c89b1"
+    "hash": "b23d70f93fe88b9bfcf8d05f46e3faa60d54cf469813e2ead871e9c9d9231ab7"
   },
   "groups": [
     {
diff --git a/testdata/diff/create_policy/disable_rls/plan.json b/testdata/diff/create_policy/disable_rls/plan.json
index bff3fcb6..0803b934 100644
--- a/testdata/diff/create_policy/disable_rls/plan.json
+++ b/testdata/diff/create_policy/disable_rls/plan.json
@@ -3,7 +3,7 @@
   "pgschema_version": "1.8.0",
   "created_at": "1970-01-01T00:00:00Z",
   "source_fingerprint": {
-    "hash": "a24989791c9ba13d2d21f70cd0405e0e509c55341872b552ab87a0c79d238ddd"
+    "hash": "a5fcd005530df97b095b020e1a8c2fb12333baf056c3a2318bc34f2157893877"
   },
   "groups": [
     {
diff --git a/testdata/diff/create_policy/drop_policy/plan.json b/testdata/diff/create_policy/drop_policy/plan.json
index b9404102..0f00feb8 100644
--- a/testdata/diff/create_policy/drop_policy/plan.json
+++ b/testdata/diff/create_policy/drop_policy/plan.json
@@ -3,7 +3,7 @@
   "pgschema_version": "1.8.0",
   "created_at": "1970-01-01T00:00:00Z",
   "source_fingerprint": {
-    "hash": "a24989791c9ba13d2d21f70cd0405e0e509c55341872b552ab87a0c79d238ddd"
+    "hash": "a5fcd005530df97b095b020e1a8c2fb12333baf056c3a2318bc34f2157893877"
   },
   "groups": [
     {
diff --git a/testdata/diff/create_policy/force_rls/plan.json b/testdata/diff/create_policy/force_rls/plan.json
index 52d6ab17..bb75c354 100644
--- a/testdata/diff/create_policy/force_rls/plan.json
+++ b/testdata/diff/create_policy/force_rls/plan.json
@@ -3,7 +3,7 @@
   "pgschema_version": "1.8.0",
   "created_at": "1970-01-01T00:00:00Z",
   "source_fingerprint": {
-    "hash": "5e4ac40b64a7ec01d1f41af5c61ba420960e98b8ac166d757ee424ea3f10474f"
+    "hash": "f26c6614d22a712e9314414c386efca5bb723c12064c63e173483f718716f193"
   },
   "groups": [
     {
diff --git a/testdata/diff/create_policy/issue_377_nested_function_in_policy/diff.sql b/testdata/diff/create_policy/issue_377_nested_function_in_policy/diff.sql
new file mode 100644
index 00000000..407496c5
--- /dev/null
+++ b/testdata/diff/create_policy/issue_377_nested_function_in_policy/diff.sql
@@ -0,0 +1 @@
+ALTER TABLE projects ADD COLUMN description text;
diff --git a/testdata/diff/create_policy/issue_377_nested_function_in_policy/new.sql b/testdata/diff/create_policy/issue_377_nested_function_in_policy/new.sql
new file mode 100644
index 00000000..6aecf891
--- /dev/null
+++ b/testdata/diff/create_policy/issue_377_nested_function_in_policy/new.sql
@@ -0,0 +1,16 @@
+CREATE FUNCTION get_user_assigned_projects() RETURNS integer[]
+LANGUAGE sql STABLE AS $$ SELECT ARRAY[1, 2, 3] $$;
+
+CREATE TABLE projects (
+    id SERIAL PRIMARY KEY,
+    name VARCHAR(100) NOT NULL,
+    description TEXT
+);
+
+ALTER TABLE projects ENABLE ROW LEVEL SECURITY;
+
+-- Policy unchanged, but table has new column
+CREATE POLICY project_access ON projects
+    FOR SELECT
+    TO PUBLIC
+    USING (id IN (SELECT unnest(get_user_assigned_projects()) AS unnest));
diff --git a/testdata/diff/create_policy/issue_377_nested_function_in_policy/old.sql b/testdata/diff/create_policy/issue_377_nested_function_in_policy/old.sql
new file mode 100644
index 00000000..d8445d68
--- /dev/null
+++ b/testdata/diff/create_policy/issue_377_nested_function_in_policy/old.sql
@@ -0,0 +1,14 @@
+CREATE FUNCTION get_user_assigned_projects() RETURNS integer[]
+LANGUAGE sql STABLE AS $$ SELECT ARRAY[1, 2, 3] $$;
+
+CREATE TABLE projects (
+    id SERIAL PRIMARY KEY,
+    name VARCHAR(100) NOT NULL
+);
+
+ALTER TABLE projects ENABLE ROW LEVEL SECURITY;
+
+CREATE POLICY project_access ON projects
+    FOR SELECT
+    TO PUBLIC
+    USING (id IN (SELECT unnest(get_user_assigned_projects()) AS unnest));
diff --git a/testdata/diff/create_policy/issue_377_nested_function_in_policy/plan.json b/testdata/diff/create_policy/issue_377_nested_function_in_policy/plan.json
new file mode 100644
index 00000000..9af0ff84
--- /dev/null
+++ b/testdata/diff/create_policy/issue_377_nested_function_in_policy/plan.json
@@ -0,0 +1,20 @@
+{
+  "version": "1.0.0",
+  "pgschema_version": "1.8.0",
+  "created_at": "1970-01-01T00:00:00Z",
+  "source_fingerprint": {
+    "hash": "37d3ebdd423c5db41ba042431c6328705f50593fe2c8f5163de497aa4eee08b8"
+  },
+  "groups": [
+    {
+      "steps": [
+        {
+          "sql": "ALTER TABLE projects ADD COLUMN description text;",
+          "type": "table.column",
+          "operation": "create",
+          "path": "public.projects.description"
+        }
+      ]
+    }
+  ]
+}
diff --git a/testdata/diff/create_policy/issue_377_nested_function_in_policy/plan.sql b/testdata/diff/create_policy/issue_377_nested_function_in_policy/plan.sql
new file mode 100644
index 00000000..407496c5
--- /dev/null
+++ b/testdata/diff/create_policy/issue_377_nested_function_in_policy/plan.sql
@@ -0,0 +1 @@
+ALTER TABLE projects ADD COLUMN description text;
diff --git a/testdata/diff/create_policy/issue_377_nested_function_in_policy/plan.txt b/testdata/diff/create_policy/issue_377_nested_function_in_policy/plan.txt
new file mode 100644
index 00000000..a2c20220
--- /dev/null
+++ b/testdata/diff/create_policy/issue_377_nested_function_in_policy/plan.txt
@@ -0,0 +1,13 @@
+Plan: 1 to modify.
+
+Summary by type:
+  tables: 1 to modify
+
+Tables:
+  ~ projects
+    + description (column)
+
+DDL to be executed:
+--------------------------------------------------
+
+ALTER TABLE projects ADD COLUMN description text;
diff --git a/testdata/diff/create_policy/remove_force_rls/plan.json b/testdata/diff/create_policy/remove_force_rls/plan.json
index 893f11e6..e6c52c8c 100644
--- a/testdata/diff/create_policy/remove_force_rls/plan.json
+++ b/testdata/diff/create_policy/remove_force_rls/plan.json
@@ -3,7 +3,7 @@
   "pgschema_version": "1.8.0",
   "created_at": "1970-01-01T00:00:00Z",
   "source_fingerprint": {
-    "hash": "0d3cfe3e8283f19f2e5ea37cfc7f2cbab91b543bf77aac99a2a912a17bc6e3f1"
+    "hash": "6d556186d2ea5db5c7aebfd47e9a7d91430bbed6f2c9052964d2d17424b6984d"
   },
   "groups": [
     {