--- a/test/TestCommon.gmk	Fri Mar 09 00:28:50 2018 +0100
+++ b/test/TestCommon.gmk	Fri Mar 02 21:00:12 2018 +0100
@@ -346,13 +346,14 @@
 endif
 
 # Problematic tests to be excluded
-PROBLEM_LISTS=$(call MixedDirs,$(wildcard ProblemList.txt))
+EXTRA_PROBLEM_LISTS :=
+PROBLEM_LISTS := ProblemList.txt $(EXTRA_PROBLEM_LISTS)
 
 # Create exclude list for this platform and arch
 ifdef NO_EXCLUDES
   JTREG_EXCLUSIONS =
 else
-  JTREG_EXCLUSIONS = $(PROBLEM_LISTS:%=-exclude:%)
+  JTREG_EXCLUSIONS = $(addprefix -exclude:, $(wildcard $(PROBLEM_LISTS)))
 endif
 
 # ------------------------------------------------------------------