diff --git a/pinc/html_page_common.inc b/pinc/html_page_common.inc
index 4bd61d843..0acdf3526 100644
--- a/pinc/html_page_common.inc
+++ b/pinc/html_page_common.inc
@@ -19,11 +19,13 @@ function output_html_header(?string $nameofpage, array $extra_args = [], bool $s
 {
     global $code_url;
 
-    static $was_output = false;
-    if ($was_output) {
+    static $output_caller = null;
+    if (!is_null($output_caller)) {
+        $loc = get_backtrace_loc();
+        error_log("output_html_header: called from $output_caller then $loc");
         return;
     }
-    $was_output = true;
+    $output_caller = get_backtrace_loc();
 
     $user = User::load_current();
 
diff --git a/pinc/slim_header.inc b/pinc/slim_header.inc
index c01e7ca6c..cba1fcccb 100644
--- a/pinc/slim_header.inc
+++ b/pinc/slim_header.inc
@@ -34,12 +34,14 @@ function slim_footer(array $extra_args = []): void
 {
     // Despite not needing to, some pages may still be calling slim_footer
     // so check to see if we've already output the footer.
-    static $was_output = false;
-    if ($was_output) {
+    static $output_caller = null;
+    if (!is_null($output_caller)) {
+        $loc = get_backtrace_loc();
+        error_log("slim_footer: called from $output_caller then $loc");
         return;
     }
 
     output_html_footer($extra_args);
 
-    $was_output = true;
+    $output_caller = get_backtrace_loc();
 }
diff --git a/tools/project_manager/generate_post_files.php b/tools/project_manager/generate_post_files.php
index 40331f2c5..f05993b20 100644
--- a/tools/project_manager/generate_post_files.php
+++ b/tools/project_manager/generate_post_files.php
@@ -67,11 +67,13 @@ function output_page_header(Project $project): void
 
     // Allow this function to be called multiple times but only output
     // the contents once.
-    static $was_output = false;
-    if ($was_output) {
+    static $output_caller = null;
+    if (!is_null($output_caller)) {
+        $loc = get_backtrace_loc();
+        error_log("output_page_header: called from $output_caller then $loc");
         return;
     }
-    $was_output = true;
+    $output_caller = get_backtrace_loc();
 
     $title = _("Generating Post Files");
     slim_header($title);