diff --git a/utils/scan-build b/utils/scan-build
index f598bb0..03d8f4d 100755
--- a/utils/scan-build
+++ b/utils/scan-build
@@ -1164,7 +1164,7 @@
 # Run the build.
 my $ExitStatus = RunBuildCommand(\@ARGV, $IgnoreErrors, $Cmd);
 
-if ($OutputFormat eq "plist") {
+if (defined $OutputFormat and $OutputFormat eq "plist") {
   Diag "Analysis run complete.\n";
   Diag "Analysis results (plist files) deposited in '$HtmlDir'\n";
 }