diff --git a/src/SConscript b/src/SConscript
index 0b66d6a62a..dcb08a3045 100644
--- a/src/SConscript
+++ b/src/SConscript
@@ -472,7 +472,7 @@ class UnitTest(Executable):
     def declare(self, env):
         sources = list(self.sources)
         for f in self.filters:
-            sources = Source.all.apply_filter(f)
+            sources += Source.all.apply_filter(f)
         objs = self.srcs_to_objs(env, sources) + env['STATIC_OBJS']
         if self.main:
             objs += env['MAIN_OBJS']
diff --git a/src/systemc/tests/SConscript b/src/systemc/tests/SConscript
index 2d713a0d8a..3b0c7c3f59 100644
--- a/src/systemc/tests/SConscript
+++ b/src/systemc/tests/SConscript
@@ -91,7 +91,7 @@ if env['USE_SYSTEMC']:
             env = env.Clone()
             sources = list(self.sources)
             for f in self.filters:
-                sources = Source.all.apply_filter(f)
+                sources += Source.all.apply_filter(f)
             objs = self.srcs_to_objs(env, sources)
             objs = objs + env['MAIN_OBJS']
             relpath = os.path.relpath(