diff --git a/mercurial/commands.py b/mercurial/commands.py
--- a/mercurial/commands.py
+++ b/mercurial/commands.py
@@ -2740,6 +2740,13 @@ def debuginstall(ui, **opts):
     fm.write('pythonlib', _("checking Python lib (%s)...\n"),
              os.path.dirname(os.__file__))
 
+    # hg version
+    hgver = util.version()
+    fm.write('hgver', _("checking Mercurial version (%s)\n"),
+             hgver.split('+')[0])
+    fm.write('hgverextra', _("checking Mercurial custom build (%s)\n"),
+             '+'.join(hgver.split('+')[1:]))
+
     # compiled modules
     fm.write('hgmodules', _("checking installed modules (%s)...\n"),
              os.path.dirname(__file__))
diff --git a/tests/test-install.t b/tests/test-install.t
--- a/tests/test-install.t
+++ b/tests/test-install.t
@@ -4,6 +4,8 @@ hg debuginstall
   checking Python executable (*) (glob)
   checking Python version (2.*) (glob)
   checking Python lib (*lib*)... (glob)
+  checking Mercurial version (*) (glob)
+  checking Mercurial custom build (*) (glob)
   checking installed modules (*mercurial)... (glob)
   checking templates (*mercurial?templates)... (glob)
   checking default template (*mercurial?templates?map-cmdline.default) (glob)
@@ -24,6 +26,8 @@ hg debuginstall JSON
     "encodingerror": null,
     "extensionserror": null,
     "hgmodules": "*mercurial", (glob)
+    "hgver": "*", (glob)
+    "hgverextra": "*", (glob)
     "problems": 0,
     "pythonexe": "*", (glob)
     "pythonlib": "*", (glob)
@@ -41,6 +45,8 @@ hg debuginstall with no username
   checking Python executable (*) (glob)
   checking Python version (2.*) (glob)
   checking Python lib (*lib*)... (glob)
+  checking Mercurial version (*) (glob)
+  checking Mercurial custom build (*) (glob)
   checking installed modules (*mercurial)... (glob)
   checking templates (*mercurial?templates)... (glob)
   checking default template (*mercurial?templates?map-cmdline.default) (glob)
@@ -62,6 +68,8 @@ path variables are expanded (~ is the sa
   checking Python executable (*) (glob)
   checking Python version (*) (glob)
   checking Python lib (*lib*)... (glob)
+  checking Mercurial version (*) (glob)
+  checking Mercurial custom build (*) (glob)
   checking installed modules (*mercurial)... (glob)
   checking templates (*mercurial?templates)... (glob)
   checking default template (*mercurial?templates?map-cmdline.default) (glob)