diff --git a/tests/modules/Makefile b/tests/modules/Makefile
index bd51b3b97..41d356a1e 100644
--- a/tests/modules/Makefile
+++ b/tests/modules/Makefile
@@ -17,6 +17,13 @@ ifeq ($(uname_S),Linux)
     LIBS = -lc
 endif
 
+# OS X 11.x doesn't have /usr/lib/libSystem.dylib and needs an explicit setting.
+ifeq ($(uname_S),Darwin)
+ifeq ("$(wildcard /usr/lib/libSystem.dylib)","")
+LIBS = -L /Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/lib -lsystem
+endif
+endif
+
 TEST_MODULES = \
     commandfilter.so \
     basics.so \