diff --git a/tests/lib/diagnostic-context-test.cpp b/tests/lib/diagnostic-context-test.cpp
index 07f3f43ed..001c92cef 100644
--- a/tests/lib/diagnostic-context-test.cpp
+++ b/tests/lib/diagnostic-context-test.cpp
@@ -39,7 +39,7 @@ namespace test{
   
   namespace { // private test setup...
     
-    const uint NUM_THREADS = 100;
+    const uint NUM_THREADS = 50;
     const uint MAX_RAND    = 1000*1000;
     
     inline bool
diff --git a/tests/lib/thread-local-test.cpp b/tests/lib/thread-local-test.cpp
index 45465045d..114ba4c05 100644
--- a/tests/lib/thread-local-test.cpp
+++ b/tests/lib/thread-local-test.cpp
@@ -38,7 +38,7 @@ namespace test{
 
   namespace { // private test setup...
     
-    const uint NUM_THREADS = 100;
+    const uint NUM_THREADS = 50;
     const uint MAX_RAND    = 5*1000*1000;