diff --git a/artiq/transforms/interleave.py b/artiq/transforms/interleave.py
index 90233462e..ab9fbbfee 100644
--- a/artiq/transforms/interleave.py
+++ b/artiq/transforms/interleave.py
@@ -26,7 +26,7 @@ def _get_duration(stmt):
             return 0
         else:
             return -1
-    elif isinstance(stmt, ast.Call) and isinstance(stmt.func, ast.Name):
+    elif isinstance(stmt, ast.Call):
         name = stmt.func.id
         if name == "delay":
             try:
diff --git a/artiq/transforms/lower_time.py b/artiq/transforms/lower_time.py
index f991cf8f6..d24583b39 100644
--- a/artiq/transforms/lower_time.py
+++ b/artiq/transforms/lower_time.py
@@ -19,7 +19,7 @@ from artiq.language.core import int64
 
 class _TimeLowerer(ast.NodeTransformer):
     def visit_Call(self, node):
-        if isinstance(node.func, ast.Name) and node.func.id == "now":
+        if node.func.id == "now":
             return ast.copy_location(ast.Name("now", ast.Load()), node)
         else:
             self.generic_visit(node)
@@ -27,8 +27,7 @@ class _TimeLowerer(ast.NodeTransformer):
 
     def visit_Expr(self, node):
         r = node
-        if (isinstance(node.value, ast.Call)
-                and isinstance(node.value.func, ast.Name)):
+        if isinstance(node.value, ast.Call):
             funcname = node.value.func.id
             if funcname == "delay":
                 r = ast.copy_location(
diff --git a/artiq/transforms/tools.py b/artiq/transforms/tools.py
index 07ce20acd..96228ac9a 100644
--- a/artiq/transforms/tools.py
+++ b/artiq/transforms/tools.py
@@ -102,7 +102,7 @@ def _is_ref_transparent(dependencies, expr):
             and _is_ref_transparent(dependencies, expr.right))
     elif isinstance(expr, ast.BoolOp):
         return all(_is_ref_transparent(dependencies, v) for v in expr.values)
-    elif isinstance(expr, ast.Call) and isinstance(expr.func, ast.Name):
+    elif isinstance(expr, ast.Call):
         return (expr.func.id in _replaceable_funcs and
             all(_is_ref_transparent(dependencies, arg) for arg in expr.args))
     else: