diff --git a/artiq/compiler/transforms/inferencer.py b/artiq/compiler/transforms/inferencer.py
index f72f01127..7d6d065b7 100644
--- a/artiq/compiler/transforms/inferencer.py
+++ b/artiq/compiler/transforms/inferencer.py
@@ -305,6 +305,7 @@ class Inferencer(algorithm.Visitor):
 
     def visit_IfExpT(self, node):
         self.generic_visit(node)
+        self._unify(node.test.type, builtins.TBool(), node.test.loc, None)
         self._unify(node.body.type, node.orelse.type,
                     node.body.loc, node.orelse.loc)
         self._unify(node.type, node.body.type,
diff --git a/artiq/test/lit/inferencer/if_expr.py b/artiq/test/lit/inferencer/if_expr.py
new file mode 100644
index 000000000..d955bc736
--- /dev/null
+++ b/artiq/test/lit/inferencer/if_expr.py
@@ -0,0 +1,6 @@
+# RUN: %python -m artiq.compiler.testbench.inferencer %s >%t
+# RUN: OutputCheck %s --file-to-check=%t
+
+# CHECK-L: def foo(val:bool)->numpy.int?:
+def foo(val):
+    return 1 if val else 0