diff --git a/test/simulator/meson.build b/test/simulator/meson.build
index e581b1a..87b675b 100644
--- a/test/simulator/meson.build
+++ b/test/simulator/meson.build
@@ -1,6 +1,7 @@
 sim_sources = [
     'hei_sim_main.cpp',
-    '../../src/isolator/hei_isolator.cpp'
+    '../../src/isolator/hei_isolator.cpp',
+    '../../src/util/hei_bit_string.cpp',
 ]
 
 sim = executable('simulator', sim_sources, \