diff --git a/docs/formatdomain.rst b/docs/formatdomain.rst
index 041dfc699d..98eb7b7481 100644
--- a/docs/formatdomain.rst
+++ b/docs/formatdomain.rst
@@ -2074,7 +2074,7 @@ are:
    =========== ============================================== =================================================== ==============
    Feature     Description                                    Value                                               Since
    =========== ============================================== =================================================== ==============
-   tb-cache    The size of translation block cache size       an integer                                          :since:`8.0.0`
+   tb-cache    The size of translation block cache size       an integer (a multiple of MiB)                      :since:`8.0.0`
    =========== ============================================== =================================================== ==============
 
 :anchor:`<a id="elementsTime"/>`
diff --git a/src/qemu/qemu_validate.c b/src/qemu/qemu_validate.c
index 2c9ccbd4fd..5592c99f3b 100644
--- a/src/qemu/qemu_validate.c
+++ b/src/qemu/qemu_validate.c
@@ -295,6 +295,22 @@ qemuValidateDomainDefFeatures(const virDomainDef *def,
             break;
 
         case VIR_DOMAIN_FEATURE_TCG:
+            if (def->features[i] == VIR_TRISTATE_SWITCH_ON) {
+                if (def->virtType != VIR_DOMAIN_VIRT_QEMU) {
+                    virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
+                                   _("TCG features are incompatible with domain type '%s'"),
+                                   virDomainVirtTypeToString(def->virtType));
+                    return -1;
+                }
+
+                if ((def->tcg_features->tb_cache & 0x3ff) != 0) {
+                    virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                                   _("tb-cache size must be an integer multiple of MiB"));
+                    return -1;
+                }
+            }
+            break;
+
         case VIR_DOMAIN_FEATURE_SMM:
         case VIR_DOMAIN_FEATURE_KVM:
         case VIR_DOMAIN_FEATURE_XEN: