diff --git a/Misc/NEWS b/Misc/NEWS
index c4a271baf5c..b3d099b2cbf 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -10,6 +10,9 @@ What's New in Python 3.1.4?
 Core and Builtins
 -----------------
 
+- Issue #11450: Don't truncate hg version info in Py_GetBuildInfo() when
+  there are many tags (e.g. when using mq).  Patch by Nadeem Vawda.
+
 - Issue #10451: memoryview objects could allow to mutate a readable buffer.
   Initial patch by Ross Lagerwall.
 
diff --git a/Modules/getbuildinfo.c b/Modules/getbuildinfo.c
index c70126d5841..ac5188126cd 100644
--- a/Modules/getbuildinfo.c
+++ b/Modules/getbuildinfo.c
@@ -42,7 +42,9 @@
 const char *
 Py_GetBuildInfo(void)
 {
-    static char buildinfo[50];
+    static char buildinfo[50 + sizeof HGVERSION +
+                          ((sizeof HGTAG > sizeof HGBRANCH) ?
+                           sizeof HGTAG : sizeof HGBRANCH)];
     const char *revision = _Py_hgversion();
     const char *sep = *revision ? ":" : "";
     const char *hgid = _Py_hgidentifier();