diff --git a/ChangeLog b/ChangeLog
index a696b657..b6d89ed8 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -24525,3 +24525,6 @@
 	the Operations Guide.
 	* Documented the 'Source' and 'Ingest' fields for Cuts in the
 	'RDLibrary' chapter of the Operations Guide.
+2023-12-07 Fred Gleason <fredg@paravelsystems.com>
+	* Modified the schema reversion 348=>347 in rddbmgr(8) to remove
+	out-of-bounds SoundPanel button entries.
diff --git a/utils/rddbmgr/revertschema.cpp b/utils/rddbmgr/revertschema.cpp
index 5c0ef5bc..e51645da 100644
--- a/utils/rddbmgr/revertschema.cpp
+++ b/utils/rddbmgr/revertschema.cpp
@@ -459,11 +459,28 @@ bool MainObject::RevertSchema(int cur_schema,int set_schema,QString *err_msg)
   // Revert 348
   //
   if((cur_schema==348)&&(set_schema<cur_schema)) {
-    // Nothing to do!
+    //
+    // Remove "out-of-bounds" data for SoundPanel buttons so they don't
+    // cause segfaults in "naive" v3.x code.
+    //
+    sql=QString("delete from `PANELS` where ")+
+      "`ROW_NO`>=5 || `COLUMN_NO`>=5";
+    if(!RDSqlQuery::apply(sql,err_msg)) {
+      return false;
+    }
+    sql=QString("delete from `EXTENDED_PANELS` where ")+
+      "`ROW_NO`>=7 || `COLUMN_NO`>=9";
+    if(!RDSqlQuery::apply(sql,err_msg)) {
+      return false;
+    }
 
     WriteSchemaVersion(--cur_schema);
   }
 
+  /************************************************************************
+   * Boundary between v3.x and v4.x
+   ************************************************************************/
+
   //
   // Revert 347
   //
diff --git a/utils/rddbmgr/updateschema.cpp b/utils/rddbmgr/updateschema.cpp
index 9b84307c..740e9f32 100644
--- a/utils/rddbmgr/updateschema.cpp
+++ b/utils/rddbmgr/updateschema.cpp
@@ -10787,6 +10787,10 @@ bool MainObject::UpdateSchema(int cur_schema,int set_schema,QString *err_msg)
     WriteSchemaVersion(++cur_schema);
   }
 
+  /************************************************************************
+   * Boundary between v3.x and v4.x
+   ************************************************************************/
+
   if((cur_schema<348)&&(set_schema>cur_schema)) {
     CheckSchedCodeRules(false);
     WriteSchemaVersion(++cur_schema);