diff --git a/artiq/compiler/ir.py b/artiq/compiler/ir.py
index e80a4af63..d96504510 100644
--- a/artiq/compiler/ir.py
+++ b/artiq/compiler/ir.py
@@ -22,14 +22,14 @@ class _Namespace:
 	def load(self, builder, name):
 		return builder.load(self.bindings[name])
 
-def _emit_expr(builder, ns, node):
+def _emit_expr(env, builder, ns, node):
 	if isinstance(node, ast.Name):
 		return ns.load(builder, node.id)
 	elif isinstance(node, ast.Num):
 		return lc.Constant.int(lc.Type.int(), node.n)
 	elif isinstance(node, ast.BinOp):
-		left = _emit_expr(builder, ns, node.left)
-		right = _emit_expr(builder, ns, node.right)
+		left = _emit_expr(env, builder, ns, node.left)
+		right = _emit_expr(env, builder, ns, node.right)
 		mapping = {
 			ast.Add: builder.add,
 			ast.Sub: builder.sub,
@@ -41,9 +41,9 @@ def _emit_expr(builder, ns, node):
 		return bf(left, right)
 	elif isinstance(node, ast.Compare):
 		comparisons = []
-		old_comparator = _emit_expr(builder, ns, node.left)
+		old_comparator = _emit_expr(env, builder, ns, node.left)
 		for op, comparator_a in zip(node.ops, node.comparators):
-			comparator = _emit_expr(builder, ns, comparator_a)
+			comparator = _emit_expr(env, builder, ns, comparator_a)
 			mapping = {
 				ast.Eq: lc.ICMP_EQ,
 				ast.NotEq: lc.ICMP_NE,
@@ -59,16 +59,22 @@ def _emit_expr(builder, ns, node):
 		for comparison in comparisons[1:]:
 			r = builder.band(r, comparison)
 		return r
+	elif isinstance(node, ast.Call):
+		if node.func.id == "syscall":
+			return env.emit_syscall(builder, node.args[0].s,
+				[_emit_expr(env, builder, ns, expr) for expr in node.args[1:]])
+		else:
+			raise NotImplementedError
 	else:
 		raise NotImplementedError
 
 def _emit_statements(env, builder, ns, stmts):
 	for stmt in stmts:
 		if isinstance(stmt, ast.Return):
-			val = _emit_expr(builder, ns, stmt.value)
+			val = _emit_expr(env, builder, ns, stmt.value)
 			builder.ret(val)
 		elif isinstance(stmt, ast.Assign):
-			val = _emit_expr(builder, ns, stmt.value)
+			val = _emit_expr(env, builder, ns, stmt.value)
 			for target in stmt.targets:
 				if isinstance(target, ast.Name):
 					ns.store(builder, val, target.id)
@@ -80,7 +86,7 @@ def _emit_statements(env, builder, ns, stmts):
 			else_block = function.append_basic_block("i_else")
 			merge_block = function.append_basic_block("i_merge")
 
-			condition = _emit_expr(builder, ns, stmt.test)
+			condition = _emit_expr(env, builder, ns, stmt.test)
 			builder.cbranch(condition, then_block, else_block)
 
 			builder.position_at_end(then_block)
@@ -98,12 +104,12 @@ def _emit_statements(env, builder, ns, stmts):
 			else_block = function.append_basic_block("w_else")
 			merge_block = function.append_basic_block("w_merge")
 
-			condition = _emit_expr(builder, ns, stmt.test)
+			condition = _emit_expr(env, builder, ns, stmt.test)
 			builder.cbranch(condition, body_block, else_block)
 
 			builder.position_at_end(body_block)
 			_emit_statements(env, builder, ns, stmt.body)
-			condition = _emit_expr(builder, ns, stmt.test)
+			condition = _emit_expr(env, builder, ns, stmt.test)
 			builder.cbranch(condition, body_block, merge_block)
 
 			builder.position_at_end(else_block)
@@ -111,13 +117,8 @@ def _emit_statements(env, builder, ns, stmts):
 			builder.branch(merge_block)
 
 			builder.position_at_end(merge_block)
-		elif isinstance(stmt, ast.Expr) and isinstance(stmt.value, ast.Call):
-			call = stmt.value
-			if call.func.id == "syscall":
-				env.emit_syscall(builder, call.args[0].s,
-					[_emit_expr(builder, ns, expr) for expr in call.args[1:]])
-			else:
-				raise NotImplementedError
+		elif isinstance(stmt, ast.Expr):
+			_emit_expr(env, builder, ns, stmt.value)
 		else:
 			raise NotImplementedError