diff --git a/src/bhyve/bhyve_firmware.c b/src/bhyve/bhyve_firmware.c
index 57ab9c7a82..8aaf05dc62 100644
--- a/src/bhyve/bhyve_firmware.c
+++ b/src/bhyve/bhyve_firmware.c
@@ -80,6 +80,9 @@ bhyveFirmwareFillDomain(bhyveConn *driver,
     if (!def->os.loader)
         def->os.loader = virDomainLoaderDefNew();
 
+    if (!def->os.loader->format)
+        def->os.loader->format = VIR_STORAGE_FILE_RAW;
+
     if (def->os.loader->format != VIR_STORAGE_FILE_RAW) {
         virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
                        _("Unsupported loader format '%1$s'"),
diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c
index 47693a49bf..2e60927799 100644
--- a/src/conf/domain_conf.c
+++ b/src/conf/domain_conf.c
@@ -3728,7 +3728,6 @@ virDomainLoaderDefNew(void)
     virDomainLoaderDef *def = NULL;
 
     def = g_new0(virDomainLoaderDef, 1);
-    def->format = VIR_STORAGE_FILE_RAW;
 
     return def;
 }
@@ -16771,10 +16770,11 @@ virDomainLoaderDefParseXMLNvram(virDomainLoaderDef *loader,
 
     if (virXMLPropEnumDefault(nvramNode, "format",
                               virStorageFileFormatTypeFromString, VIR_XML_PROP_NONE,
-                              &format, VIR_STORAGE_FILE_RAW) < 0) {
+                              &format, VIR_STORAGE_FILE_NONE) < 0) {
         return -1;
     }
-    if (format != VIR_STORAGE_FILE_RAW &&
+    if (format &&
+        format != VIR_STORAGE_FILE_RAW &&
         format != VIR_STORAGE_FILE_QCOW2) {
         virReportError(VIR_ERR_XML_ERROR,
                        _("Unsupported nvram format '%1$s'"),
@@ -16860,10 +16860,11 @@ virDomainLoaderDefParseXMLLoader(virDomainLoaderDef *loader,
 
     if (virXMLPropEnumDefault(loaderNode, "format",
                               virStorageFileFormatTypeFromString, VIR_XML_PROP_NONE,
-                              &format, VIR_STORAGE_FILE_RAW) < 0) {
+                              &format, VIR_STORAGE_FILE_NONE) < 0) {
         return -1;
     }
-    if (format != VIR_STORAGE_FILE_RAW &&
+    if (format &&
+        format != VIR_STORAGE_FILE_RAW &&
         format != VIR_STORAGE_FILE_QCOW2) {
         virReportError(VIR_ERR_XML_ERROR,
                        _("Unsupported loader format '%1$s'"),
@@ -16894,7 +16895,9 @@ virDomainLoaderDefParseXML(virDomainLoaderDef *loader,
                                          loaderNode) < 0)
         return -1;
 
-    if (loader->nvram && loader->format != loader->nvram->format) {
+    if (loader->nvram &&
+        loader->format && loader->nvram->format &&
+        loader->format != loader->nvram->format) {
         virReportError(VIR_ERR_XML_ERROR,
                        _("Format mismatch: loader.format='%1$s' nvram.format='%2$s'"),
                        virStorageFileFormatTypeToString(loader->format),
@@ -26224,7 +26227,8 @@ virDomainLoaderDefFormatNvram(virBuffer *buf,
                 return -1;
         }
 
-        if (src->format != VIR_STORAGE_FILE_RAW) {
+        if (src->format &&
+            src->format != VIR_STORAGE_FILE_RAW) {
             virBufferEscapeString(&attrBuf, " format='%s'",
                                   virStorageFileFormatTypeToString(src->format));
         }
@@ -26262,7 +26266,8 @@ virDomainLoaderDefFormat(virBuffer *buf,
                           virTristateBoolTypeToString(loader->stateless));
     }
 
-    if (loader->format != VIR_STORAGE_FILE_RAW) {
+    if (loader->format &&
+        loader->format != VIR_STORAGE_FILE_RAW) {
         virBufferEscapeString(&loaderAttrBuf, " format='%s'",
                               virStorageFileFormatTypeToString(loader->format));
     }
diff --git a/src/libxl/libxl_conf.c b/src/libxl/libxl_conf.c
index a1c76935b6..14ad320023 100644
--- a/src/libxl/libxl_conf.c
+++ b/src/libxl/libxl_conf.c
@@ -654,11 +654,16 @@ libxlMakeDomBuildInfo(virDomainDef *def,
             b_info->u.hvm.system_firmware = g_strdup(def->os.loader->path);
         }
 
-        if (def->os.loader && def->os.loader->format != VIR_STORAGE_FILE_RAW) {
-            virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
-                           _("Unsupported loader format '%1$s'"),
-                           virStorageFileFormatTypeToString(def->os.loader->format));
-            return -1;
+        if (def->os.loader) {
+            if (!def->os.loader->format)
+                def->os.loader->format = VIR_STORAGE_FILE_RAW;
+
+            if (def->os.loader->format != VIR_STORAGE_FILE_RAW) {
+                virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
+                               _("Unsupported loader format '%1$s'"),
+                               virStorageFileFormatTypeToString(def->os.loader->format));
+                return -1;
+            }
         }
 
         if (def->emulator) {
diff --git a/src/libxl/xen_xl.c b/src/libxl/xen_xl.c
index 1cc42fa59f..ab1941454d 100644
--- a/src/libxl/xen_xl.c
+++ b/src/libxl/xen_xl.c
@@ -115,6 +115,7 @@ xenParseXLOS(virConf *conf, virDomainDef *def, virCaps *caps)
 
         if (bios && STREQ(bios, "ovmf")) {
             def->os.loader = virDomainLoaderDefNew();
+            def->os.loader->format = VIR_STORAGE_FILE_RAW;
             def->os.loader->type = VIR_DOMAIN_LOADER_TYPE_PFLASH;
             def->os.loader->readonly = VIR_TRISTATE_BOOL_YES;
             if (bios_path)
@@ -126,6 +127,7 @@ xenParseXLOS(virConf *conf, virDomainDef *def, virCaps *caps)
                 if (caps->guests[i]->ostype == VIR_DOMAIN_OSTYPE_HVM &&
                     caps->guests[i]->arch.id == def->os.arch) {
                     def->os.loader = virDomainLoaderDefNew();
+                    def->os.loader->format = VIR_STORAGE_FILE_RAW;
                     def->os.loader->path = g_strdup(caps->guests[i]->arch.defaultInfo.loader);
                 }
             }
diff --git a/src/libxl/xen_xm.c b/src/libxl/xen_xm.c
index 0031d6cbc6..5705a5ec0c 100644
--- a/src/libxl/xen_xm.c
+++ b/src/libxl/xen_xm.c
@@ -43,6 +43,7 @@ xenParseXMOS(virConf *conf, virDomainDef *def)
         g_autofree char *boot = NULL;
 
         def->os.loader = virDomainLoaderDefNew();
+        def->os.loader->format = VIR_STORAGE_FILE_RAW;
 
         if (xenConfigCopyString(conf, "kernel", &def->os.loader->path) < 0)
             return -1;
diff --git a/src/qemu/qemu_firmware.c b/src/qemu/qemu_firmware.c
index ebaf32cf71..3dcd139a47 100644
--- a/src/qemu/qemu_firmware.c
+++ b/src/qemu/qemu_firmware.c
@@ -1082,6 +1082,11 @@ qemuFirmwareEnsureNVRAM(virDomainDef *def,
     if (loader->stateless == VIR_TRISTATE_BOOL_YES)
         return;
 
+    /* If the NVRAM format hasn't been set yet, inherit the same as
+     * the loader */
+    if (loader->nvram && !loader->nvram->format)
+        loader->nvram->format = loader->format;
+
     /* If the source already exists and is fully specified, including
      * the path, leave it alone */
     if (loader->nvram && loader->nvram->path)
@@ -1328,7 +1333,7 @@ qemuFirmwareMatchDomain(const virDomainDef *def,
                       flash->executable.format);
             return false;
         }
-        if (loader &&
+        if (loader && loader->format &&
             STRNEQ(flash->executable.format, virStorageFileFormatTypeToString(loader->format))) {
             VIR_DEBUG("Discarding loader with mismatching flash format '%s' != '%s'",
                       flash->executable.format,
@@ -1342,7 +1347,7 @@ qemuFirmwareMatchDomain(const virDomainDef *def,
                           flash->nvram_template.format);
                 return false;
             }
-            if (loader && loader->nvram &&
+            if (loader && loader->nvram && loader->nvram->format &&
                 STRNEQ(flash->nvram_template.format, virStorageFileFormatTypeToString(loader->nvram->format))) {
                 VIR_DEBUG("Discarding loader with mismatching nvram template format '%s' != '%s'",
                           flash->nvram_template.format,
@@ -1630,7 +1635,8 @@ qemuFirmwareFillDomainLegacy(virQEMUDriver *driver,
         return 1;
     }
 
-    if (loader->format != VIR_STORAGE_FILE_RAW) {
+    if (loader->format &&
+        loader->format != VIR_STORAGE_FILE_RAW) {
         VIR_DEBUG("Ignoring legacy entries for loader with flash format '%s'",
                   virStorageFileFormatTypeToString(loader->format));
         return 1;
@@ -1793,6 +1799,7 @@ qemuFirmwareFillDomain(virQEMUDriver *driver,
         return -1;
 
     if (loader &&
+        loader->format &&
         loader->format != VIR_STORAGE_FILE_RAW &&
         loader->format != VIR_STORAGE_FILE_QCOW2) {
         virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
@@ -1801,6 +1808,7 @@ qemuFirmwareFillDomain(virQEMUDriver *driver,
         return -1;
     }
     if (nvram &&
+        nvram->format &&
         nvram->format != VIR_STORAGE_FILE_RAW &&
         nvram->format != VIR_STORAGE_FILE_QCOW2) {
         virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
@@ -1831,8 +1839,19 @@ qemuFirmwareFillDomain(virQEMUDriver *driver,
          * CODE:NVRAM pairs that might have been provided at build
          * time */
         if (!autoSelection) {
-            if (qemuFirmwareFillDomainLegacy(driver, def) < 0)
+            if ((ret = qemuFirmwareFillDomainLegacy(driver, def)) < 0)
                 return -1;
+
+            /* If we've gotten this far without finding a match, it
+             * means that we're dealing with a set of completely
+             * custom paths. In that case, unless the user has
+             * specified otherwise, we have to assume that they're in
+             * raw format */
+            if (ret == 1) {
+                if (loader && !loader->format) {
+                    loader->format = VIR_STORAGE_FILE_RAW;
+                }
+            }
         } else {
             virReportError(VIR_ERR_OPERATION_FAILED,
                            _("Unable to find any firmware to satisfy '%1$s'"),
diff --git a/tests/qemuxml2argvdata/firmware-auto-efi-format-mismatch.x86_64-latest.args b/tests/qemuxml2argvdata/firmware-auto-efi-format-mismatch.x86_64-latest.args
new file mode 100644
index 0000000000..e8d7d580f7
--- /dev/null
+++ b/tests/qemuxml2argvdata/firmware-auto-efi-format-mismatch.x86_64-latest.args
@@ -0,0 +1,38 @@
+LC_ALL=C \
+PATH=/bin \
+HOME=/var/lib/libvirt/qemu/domain--1-guest \
+USER=test \
+LOGNAME=test \
+XDG_DATA_HOME=/var/lib/libvirt/qemu/domain--1-guest/.local/share \
+XDG_CACHE_HOME=/var/lib/libvirt/qemu/domain--1-guest/.cache \
+XDG_CONFIG_HOME=/var/lib/libvirt/qemu/domain--1-guest/.config \
+/usr/bin/qemu-system-x86_64 \
+-name guest=guest,debug-threads=on \
+-S \
+-object '{"qom-type":"secret","id":"masterKey0","format":"raw","file":"/var/lib/libvirt/qemu/domain--1-guest/master-key.aes"}' \
+-blockdev '{"driver":"file","filename":"/usr/share/edk2/ovmf/OVMF_CODE_4M.secboot.qcow2","node-name":"libvirt-pflash0-storage","auto-read-only":true,"discard":"unmap"}' \
+-blockdev '{"node-name":"libvirt-pflash0-format","read-only":true,"driver":"qcow2","file":"libvirt-pflash0-storage"}' \
+-blockdev '{"driver":"file","filename":"/path/to/guest_VARS.qcow2","node-name":"libvirt-pflash1-storage","auto-read-only":true,"discard":"unmap"}' \
+-blockdev '{"node-name":"libvirt-pflash1-format","read-only":false,"driver":"qcow2","file":"libvirt-pflash1-storage"}' \
+-machine pc-q35-4.0,usb=off,smm=on,dump-guest-core=off,memory-backend=pc.ram,pflash0=libvirt-pflash0-format,pflash1=libvirt-pflash1-format,acpi=on \
+-accel kvm \
+-cpu qemu64 \
+-global driver=cfi.pflash01,property=secure,value=on \
+-m size=1048576k \
+-object '{"qom-type":"memory-backend-ram","id":"pc.ram","size":1073741824}' \
+-overcommit mem-lock=off \
+-smp 1,sockets=1,cores=1,threads=1 \
+-uuid 63840878-0deb-4095-97e6-fc444d9bc9fa \
+-display none \
+-no-user-config \
+-nodefaults \
+-chardev socket,id=charmonitor,fd=1729,server=on,wait=off \
+-mon chardev=charmonitor,id=monitor,mode=control \
+-rtc base=utc \
+-no-shutdown \
+-boot strict=on \
+-audiodev '{"id":"audio1","driver":"none"}' \
+-global ICH9-LPC.noreboot=off \
+-watchdog-action reset \
+-sandbox on,obsolete=deny,elevateprivileges=deny,spawn=deny,resourcecontrol=deny \
+-msg timestamp=on
diff --git a/tests/qemuxml2argvdata/firmware-auto-efi-format-mismatch.x86_64-latest.err b/tests/qemuxml2argvdata/firmware-auto-efi-format-mismatch.x86_64-latest.err
deleted file mode 100644
index abfdfc4357..0000000000
--- a/tests/qemuxml2argvdata/firmware-auto-efi-format-mismatch.x86_64-latest.err
+++ /dev/null
@@ -1 +0,0 @@
-XML error: Format mismatch: loader.format='qcow2' nvram.format='raw'
diff --git a/tests/qemuxml2argvdata/firmware-auto-efi-format-mismatch.xml b/tests/qemuxml2argvdata/firmware-auto-efi-format-mismatch.xml
index 6613d9e9a9..75fa44fd20 100644
--- a/tests/qemuxml2argvdata/firmware-auto-efi-format-mismatch.xml
+++ b/tests/qemuxml2argvdata/firmware-auto-efi-format-mismatch.xml
@@ -6,7 +6,7 @@
   <os firmware='efi'>
     <type arch='x86_64' machine='pc-q35-4.0'>hvm</type>
     <loader format='qcow2'/>
-    <nvram>/path/to/guest_VARS.fd</nvram>
+    <nvram>/path/to/guest_VARS.qcow2</nvram>
   </os>
   <features>
     <acpi/>
diff --git a/tests/qemuxml2argvdata/firmware-auto-efi-loader-secure-abi-update.x86_64-latest.args b/tests/qemuxml2argvdata/firmware-auto-efi-loader-secure-abi-update.x86_64-latest.args
index 48f357cbf9..790fb619e8 100644
--- a/tests/qemuxml2argvdata/firmware-auto-efi-loader-secure-abi-update.x86_64-latest.args
+++ b/tests/qemuxml2argvdata/firmware-auto-efi-loader-secure-abi-update.x86_64-latest.args
@@ -10,10 +10,10 @@ XDG_CONFIG_HOME=/var/lib/libvirt/qemu/domain--1-guest/.config \
 -name guest=guest,debug-threads=on \
 -S \
 -object '{"qom-type":"secret","id":"masterKey0","format":"raw","file":"/var/lib/libvirt/qemu/domain--1-guest/master-key.aes"}' \
--blockdev '{"driver":"file","filename":"/usr/share/edk2/ovmf/OVMF_CODE.secboot.fd","node-name":"libvirt-pflash0-storage","auto-read-only":true,"discard":"unmap"}' \
--blockdev '{"node-name":"libvirt-pflash0-format","read-only":true,"driver":"raw","file":"libvirt-pflash0-storage"}' \
--blockdev '{"driver":"file","filename":"/var/lib/libvirt/qemu/nvram/guest_VARS.fd","node-name":"libvirt-pflash1-storage","auto-read-only":true,"discard":"unmap"}' \
--blockdev '{"node-name":"libvirt-pflash1-format","read-only":false,"driver":"raw","file":"libvirt-pflash1-storage"}' \
+-blockdev '{"driver":"file","filename":"/usr/share/edk2/ovmf/OVMF_CODE_4M.secboot.qcow2","node-name":"libvirt-pflash0-storage","auto-read-only":true,"discard":"unmap"}' \
+-blockdev '{"node-name":"libvirt-pflash0-format","read-only":true,"driver":"qcow2","file":"libvirt-pflash0-storage"}' \
+-blockdev '{"driver":"file","filename":"/var/lib/libvirt/qemu/nvram/guest_VARS.qcow2","node-name":"libvirt-pflash1-storage","auto-read-only":true,"discard":"unmap"}' \
+-blockdev '{"node-name":"libvirt-pflash1-format","read-only":false,"driver":"qcow2","file":"libvirt-pflash1-storage"}' \
 -machine pc-q35-4.0,usb=off,smm=on,dump-guest-core=off,memory-backend=pc.ram,pflash0=libvirt-pflash0-format,pflash1=libvirt-pflash1-format,acpi=on \
 -accel kvm \
 -cpu qemu64 \
diff --git a/tests/qemuxml2argvtest.c b/tests/qemuxml2argvtest.c
index 1436e3724c..7df044e03b 100644
--- a/tests/qemuxml2argvtest.c
+++ b/tests/qemuxml2argvtest.c
@@ -1115,7 +1115,7 @@ mymain(void)
     DO_TEST_CAPS_LATEST("firmware-auto-efi-format-nvram-qcow2-network-nbd");
     DO_TEST_CAPS_ARCH_LATEST("firmware-auto-efi-format-loader-raw", "aarch64");
     DO_TEST_CAPS_ARCH_LATEST_ABI_UPDATE("firmware-auto-efi-format-loader-raw-abi-update", "aarch64");
-    DO_TEST_CAPS_LATEST_PARSE_ERROR("firmware-auto-efi-format-mismatch");
+    DO_TEST_CAPS_LATEST("firmware-auto-efi-format-mismatch");
 
     DO_TEST_NOCAPS("clock-utc");
     DO_TEST_NOCAPS("clock-localtime");
diff --git a/tests/qemuxml2xmloutdata/firmware-auto-efi-loader-secure-abi-update.x86_64-latest.xml b/tests/qemuxml2xmloutdata/firmware-auto-efi-loader-secure-abi-update.x86_64-latest.xml
index 332d931ba1..f4ff7a0fc2 100644
--- a/tests/qemuxml2xmloutdata/firmware-auto-efi-loader-secure-abi-update.x86_64-latest.xml
+++ b/tests/qemuxml2xmloutdata/firmware-auto-efi-loader-secure-abi-update.x86_64-latest.xml
@@ -10,8 +10,8 @@
       <feature enabled='yes' name='enrolled-keys'/>
       <feature enabled='yes' name='secure-boot'/>
     </firmware>
-    <loader readonly='yes' secure='yes' type='pflash'>/usr/share/edk2/ovmf/OVMF_CODE.secboot.fd</loader>
-    <nvram template='/usr/share/edk2/ovmf/OVMF_VARS.secboot.fd'>/var/lib/libvirt/qemu/nvram/guest_VARS.fd</nvram>
+    <loader readonly='yes' secure='yes' type='pflash' format='qcow2'>/usr/share/edk2/ovmf/OVMF_CODE_4M.secboot.qcow2</loader>
+    <nvram template='/usr/share/edk2/ovmf/OVMF_VARS_4M.secboot.qcow2' format='qcow2'>/var/lib/libvirt/qemu/nvram/guest_VARS.qcow2</nvram>
     <boot dev='hd'/>
   </os>
   <features>