diff --git a/nss/coreconf/config.gypi b/nss/coreconf/config.gypi
index ae4c708..42633fc 100644
--- a/nss/coreconf/config.gypi
+++ b/nss/coreconf/config.gypi
@@ -622,7 +622,7 @@
           'VCCLCompilerTool': {
             'Optimization': '<(debug_optimization_level)',
             'BasicRuntimeChecks': '3',
-            'RuntimeLibrary': '2', # /MD
+            'RuntimeLibrary': '3', # /MDd
             'DebugInformationFormat': '3',
           },
           'VCLinkerTool': {