diff --git a/lib/http_proxy.c b/lib/http_proxy.c
index 845ba2e8f..5ccd656bf 100644
--- a/lib/http_proxy.c
+++ b/lib/http_proxy.c
@@ -54,6 +54,19 @@ static bool hd_name_eq(const char *n1, size_t n1len,
   return (n1len == n2len) ? curl_strnequal(n1, n2, n1len) : FALSE;
 }
 
+/* DEBUG helper: show what we are comparing.
+   Only useful with -v since infof prints in verbose mode. */
+static void debug_hdrcmp(struct Curl_easy *data,
+                         const char *name, size_t namelen,
+                         const char *label,
+                         const char *cstr, size_t clen)
+{
+  infof(data,
+        "DEBUG hdrcmp %-18s name='%.*s' len=%zu  const='%s' len=%zu  => %s",
+        label, (int)namelen, name, namelen, cstr, clen,
+        hd_name_eq(name, namelen, cstr, clen) ? "MATCH" : "NO MATCH");
+}
+
 static CURLcode dynhds_add_custom(struct Curl_easy *data,
                                   bool is_connect, int httpversion,
                                   struct dynhds *hds)
@@ -143,6 +156,21 @@ static CURLcode dynhds_add_custom(struct Curl_easy *data,
       }
 
       DEBUGASSERT(name && value);
+      /* Show comparisons so we can see why branches are or are not taken. */
+      if(data->set.verbose) {
+        debug_hdrcmp(data, name, namelen, "Host:",
+                     STRCONST("Host:"));
+        debug_hdrcmp(data, name, namelen, "Content-Type:",
+                     STRCONST("Content-Type:"));
+        debug_hdrcmp(data, name, namelen, "Content-Length:",
+                     STRCONST("Content-Length:"));
+        debug_hdrcmp(data, name, namelen, "Transfer-Encoding:",
+                     STRCONST("Transfer-Encoding:"));
+        debug_hdrcmp(data, name, namelen, "Authorization:",
+                     STRCONST("Authorization:"));
+        debug_hdrcmp(data, name, namelen, "Cookie:",
+                     STRCONST("Cookie:"));
+      }
       if(data->state.aptr.host &&
          /* a Host: header was sent already, do not pass on any custom Host:
             header as that will produce *two* in the same request! */