diff --git a/talk/build/common.gypi b/talk/build/common.gypi
index c81297482..63ad9abf6 100644
--- a/talk/build/common.gypi
+++ b/talk/build/common.gypi
@@ -114,6 +114,16 @@
         ],
       }],
       ['os_posix==1', {
+        'configurations': {
+          'Debug_Base': {
+            'defines': [
+              # Chromium's build/common.gypi defines this for all posix _except_
+              # for ios & mac.  We want it there as well, e.g. because ASSERT
+              # and friends trigger off of it.
+              '_DEBUG',
+            ],
+          },
+        },
         'defines': [
           'HASH_NAMESPACE=__gnu_cxx',
           'POSIX',