diff --git a/changes-entries/1820750.txt b/changes-entries/1820750.txt
new file mode 100644
index 00000000000..a0adca8728d
--- /dev/null
+++ b/changes-entries/1820750.txt
@@ -0,0 +1,4 @@
+  *) mod_headers: 'RequestHeader set|edit|edit_r Content-Type X' could
+     inadvertently modify the Content-Type _response_ header. Applies to
+     Content-Type only and likely to only affect static file responses.
+     [Eric Covener]
diff --git a/modules/metadata/mod_headers.c b/modules/metadata/mod_headers.c
index 4838bd6cd0d..57da3fc538d 100644
--- a/modules/metadata/mod_headers.c
+++ b/modules/metadata/mod_headers.c
@@ -782,14 +782,16 @@ static int do_headers_fixup(request_rec *r, apr_table_t *headers,
             }
             break;
         case hdr_set:
-            if (!ap_cstr_casecmp(hdr->header, "Content-Type")) {
+            if (r->headers_in != headers &&
+                !ap_cstr_casecmp(hdr->header, "Content-Type")) {
                  ap_set_content_type_ex(r, process_tags(hdr, r), 1);
             }
             apr_table_setn(headers, hdr->header, process_tags(hdr, r));
             break;
         case hdr_setifempty:
             if (NULL == apr_table_get(headers, hdr->header)) {
-                if (!ap_cstr_casecmp(hdr->header, "Content-Type")) {
+                if (r->headers_in != headers &&
+                    !ap_cstr_casecmp(hdr->header, "Content-Type")) {
                     ap_set_content_type_ex(r, process_tags(hdr, r), 1);
                 }
                 apr_table_setn(headers, hdr->header, process_tags(hdr, r));
@@ -797,6 +799,10 @@ static int do_headers_fixup(request_rec *r, apr_table_t *headers,
             break;
         case hdr_unset:
             apr_table_unset(headers, hdr->header);
+            if (r->headers_in != headers &&
+                !ap_cstr_casecmp(hdr->header, "Content-Type")) {
+                ap_set_content_type(r, NULL);
+            }
             break;
         case hdr_echo:
             v.r = r;
@@ -809,7 +815,7 @@ static int do_headers_fixup(request_rec *r, apr_table_t *headers,
                 const char *repl = process_regexp(hdr, r->content_type, r);
                 if (repl == NULL)
                     return 0;
-                ap_set_content_type_ex(r, repl, 1);
+                if (r->headers_in != headers) ap_set_content_type_ex(r, repl, 1);
             }
             if (apr_table_get(headers, hdr->header)) {
                 edit_do ed;