diff --git a/hw/arm/virt.c b/hw/arm/virt.c
index 0c65fe38a0..371147f3ae 100644
--- a/hw/arm/virt.c
+++ b/hw/arm/virt.c
@@ -2173,7 +2173,7 @@ static void virt_set_oem_id(Object *obj, const char *value, Error **errp)
         return;
     }
 
-    strncpy(vms->oem_id, value, len + 1);
+    strncpy(vms->oem_id, value, 6);
 }
 
 static char *virt_get_oem_table_id(Object *obj, Error **errp)
@@ -2194,7 +2194,7 @@ static void virt_set_oem_table_id(Object *obj, const char *value,
                    "User specified oem-table-id value is bigger than 8 bytes in size");
         return;
     }
-    strncpy(vms->oem_table_id, value, len + 1);
+    strncpy(vms->oem_table_id, value, 8);
 }
 
 
diff --git a/hw/i386/microvm.c b/hw/i386/microvm.c
index 1dc2956e72..4e0cf4c522 100644
--- a/hw/i386/microvm.c
+++ b/hw/i386/microvm.c
@@ -668,7 +668,7 @@ static void microvm_machine_set_oem_id(Object *obj, const char *value,
         return;
     }
 
-    strncpy(mms->oem_id, value, len + 1);
+    strncpy(mms->oem_id, value, 6);
 }
 
 static char *microvm_machine_get_oem_table_id(Object *obj, Error **errp)
@@ -690,7 +690,7 @@ static void microvm_machine_set_oem_table_id(Object *obj, const char *value,
           "8 bytes in size");
         return;
     }
-    strncpy(mms->oem_table_id, value, len + 1);
+    strncpy(mms->oem_table_id, value, 8);
 }
 
 static void microvm_machine_initfn(Object *obj)
diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index 437977c49e..8aa85dec54 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -1630,7 +1630,7 @@ static void pc_machine_set_oem_id(Object *obj, const char *value, Error **errp)
         return;
     }
 
-    strncpy(pcms->oem_id, value, len + 1);
+    strncpy(pcms->oem_id, value, 6);
 }
 
 static char *pc_machine_get_oem_table_id(Object *obj, Error **errp)
@@ -1652,7 +1652,7 @@ static void pc_machine_set_oem_table_id(Object *obj, const char *value,
           "8 bytes in size");
         return;
     }
-    strncpy(pcms->oem_table_id, value, len + 1);
+    strncpy(pcms->oem_table_id, value, 8);
 }
 
 static void pc_machine_initfn(Object *obj)