diff --git a/docs/env.md b/docs/env.md
index 1e0205c2c..0085bec60 100644
--- a/docs/env.md
+++ b/docs/env.md
@@ -18,6 +18,7 @@ with a non-standard filesystem layout.
 * `FWUPD_DBUS_SOCKET` is used to set the socket filename if running without a dbus-daemon
 * `FWUPD_DOWNLOAD_VERBOSE` can be used to show wget or curl output
 * `FWUPD_PROFILE` can be used to set the profile traceback threshold value in ms
+* `FWUPD_FUZZER_RUNNING` if the firmware format is being fuzzed
 * standard glibc variables like `LANG` are also honored for CLI tools that are translated
 * libcurl respects the session proxy, e.g. `http_proxy`, `all_proxy`, `sftp_proxy` and `no_proxy`
 
diff --git a/libfwupdplugin/fu-fuzzer-firmware.c.in b/libfwupdplugin/fu-fuzzer-firmware.c.in
index d7db2d208..bc1e84513 100644
--- a/libfwupdplugin/fu-fuzzer-firmware.c.in
+++ b/libfwupdplugin/fu-fuzzer-firmware.c.in
@@ -16,6 +16,7 @@ LLVMFuzzerTestOneInput(const guint8 *data, gsize size)
 	gboolean ret;
 
 	(void)g_setenv("G_DEBUG", "fatal-criticals", FALSE);
+	(void)g_setenv("FWUPD_FUZZER_RUNNING", "1", TRUE);
 	ret = fu_firmware_parse(firmware, fw, FWUPD_INSTALL_FLAG_NONE, NULL);
 	if (!ret && fu_firmware_has_flag(firmware, FU_FIRMWARE_FLAG_HAS_CHECKSUM)) {
 		g_clear_object(&firmware);
diff --git a/plugins/bcm57xx/fu-bcm57xx-dict-image.c b/plugins/bcm57xx/fu-bcm57xx-dict-image.c
index a8b1b92bc..0a5c9c371 100644
--- a/plugins/bcm57xx/fu-bcm57xx-dict-image.c
+++ b/plugins/bcm57xx/fu-bcm57xx-dict-image.c
@@ -117,7 +117,8 @@ fu_bcm57xx_dict_image_ensure_id(FuBcm57xxDictImage *self)
 		}
 	}
 	id = g_strdup_printf("dict-%02x-%02x", self->target, self->kind);
-	g_warning("falling back to %s, please report", id);
+	if (g_getenv("FWUPD_FUZZER_RUNNING") == NULL)
+		g_warning("falling back to %s, please report", id);
 	fu_firmware_set_id(FU_FIRMWARE(self), id);
 }
 
diff --git a/plugins/uf2/fu-uf2-firmware.c b/plugins/uf2/fu-uf2-firmware.c
index 0e76f6143..1b6444407 100644
--- a/plugins/uf2/fu-uf2-firmware.c
+++ b/plugins/uf2/fu-uf2-firmware.c
@@ -198,7 +198,8 @@ fu_uf2_firmware_parse_chunk(FuUf2Firmware *self, FuChunk *chk, GByteArray *tmp,
 					return FALSE;
 				fu_firmware_set_id(FU_FIRMWARE(self), utf8buf);
 			} else {
-				g_warning("unknown tag 0x%06x", tag);
+				if (g_getenv("FWUPD_FUZZER_RUNNING") == NULL)
+					g_warning("unknown tag 0x%06x", tag);
 			}
 
 			/* next! */