diff --git a/ChangeLog b/ChangeLog
index 5a653d13..9a9d3832 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -23635,3 +23635,6 @@
 	* Added a file format check to the 'Image Manager' dialog in
 	rdadmin(1) to ensure that only JPEG or PNG formatted image files can
 	be imported.
+2022-11-09 Fred Gleason <fredg@paravelsystems.com>
+	* Added an image format check to rddbmgr(8) to prevent it from
+	attempting to generate thumbnail images from non-JPEG/PNG images.
diff --git a/lib/rdconf.cpp b/lib/rdconf.cpp
index 06b498a1..51766f10 100644
--- a/lib/rdconf.cpp
+++ b/lib/rdconf.cpp
@@ -1149,3 +1149,33 @@ QString RDMimeType(const QString &filename,bool *ok)
 
   return ret;
 }
+
+
+QString RDMimeType(const QByteArray &data,bool *ok)
+{
+  QStringList args;
+  QString ret;
+  QByteArray ret_data;
+
+  args.push_back("--mime-type");
+  args.push_back("-");
+  QProcess *proc=new QProcess();
+  proc->start("/usr/bin/file",args);
+  proc->waitForStarted();
+  proc->write(data);
+  proc->closeWriteChannel();
+  proc->waitForFinished();
+  if((proc->exitStatus()!=QProcess::NormalExit)||(proc->exitCode()!=0)) {
+    *ok=false;
+    delete proc;
+    return ret;
+  }
+  *ok=true;
+
+  ret=QString(proc->readAllStandardOutput()).
+    split(":",QString::SkipEmptyParts).last().trimmed();
+
+  delete proc;
+
+  return ret;
+}
diff --git a/lib/rdconf.h b/lib/rdconf.h
index 535487ec..b7ba3602 100644
--- a/lib/rdconf.h
+++ b/lib/rdconf.h
@@ -112,6 +112,7 @@ int RDCheckExitCode(const QString &msg,int exit_code);
 int RDCheckExitCode(RDConfig *config,const QString &msg,int exit_code);
 int RDCheckReturnCode(const QString &msg,int code,int ok_value);
 QString RDMimeType(const QString &filename,bool *ok);
+QString RDMimeType(const QByteArray &data,bool *ok);
 
 
 #endif   // RDCONF_H
diff --git a/utils/rddbmgr/updateschema.cpp b/utils/rddbmgr/updateschema.cpp
index d94cf674..b58fa92d 100644
--- a/utils/rddbmgr/updateschema.cpp
+++ b/utils/rddbmgr/updateschema.cpp
@@ -19,6 +19,7 @@
 //
 
 #include <rdcart.h>
+#include <rdconf.h>
 #include <rddb.h>
 #include <rdescape_string.h>
 #include <rdfeed.h>
@@ -36,6 +37,7 @@ bool MainObject::UpdateSchema(int cur_schema,int set_schema,QString *err_msg)
   QString tablename;
   RDCart *cart;
   bool length_update_required=false;
+  bool ok=false;
 
   if(!db_start_datetime.isNull()) {
     QDateTime now=QDateTime::currentDateTime();
@@ -11292,22 +11294,37 @@ bool MainObject::UpdateSchema(int cur_schema,int set_schema,QString *err_msg)
       return false;
     }
     sql=QString("select ")+
-      "`ID`,"+    // 00
-      "`DATA` "+  // 01
+      "`ID`,"+            // 00
+      "`DATA`,"+          // 01
+      "`FEED_KEY_NAME`,"  // 02
+      "`DESCRIPTION` "+   // 03
       "from `FEED_IMAGES`";
     q=new RDSqlQuery(sql);
     while(q->next()) {
-      sql=QString("update `FEED_IMAGES` set ")+
-	"`DATA_MID_THUMB`="+
-	RDEscapeBlob(RDIMResizeImage(q->value(1).toByteArray(),
-				     RD_MID_THUMB_SIZE))+","+
-	"`DATA_SMALL_THUMB`="+
-	RDEscapeBlob(RDIMResizeImage(q->value(1).toByteArray(),
-				     RD_SMALL_THUMB_SIZE))+" "+
-	QString::asprintf("where `ID`=%u",q->value(0).toUInt());
-      if(!RDSqlQuery::apply(sql,err_msg)) {
+      QString mimetype=RDMimeType(q->value(1).toByteArray(),&ok);
+      if(!ok) {
+	*err_msg=tr("unable to determine image file type");
 	return false;
       }
+      if((mimetype=="image/jpeg")||(mimetype=="image/png")) {
+	sql=QString("update `FEED_IMAGES` set ")+
+	  "`DATA_MID_THUMB`="+
+	  RDEscapeBlob(RDIMResizeImage(q->value(1).toByteArray(),
+				       RD_MID_THUMB_SIZE))+","+
+	  "`DATA_SMALL_THUMB`="+
+	  RDEscapeBlob(RDIMResizeImage(q->value(1).toByteArray(),
+				       RD_SMALL_THUMB_SIZE))+" "+
+	  QString::asprintf("where `ID`=%u",q->value(0).toUInt());
+	if(!RDSqlQuery::apply(sql,err_msg)) {
+	  return false;
+	}
+      }
+      else {
+	fprintf(stderr,"rddbmgr: image %u:\"%s\" in RSS feed \"%s\" is not in JPEG or PNG format, skipping thumbnail generation\n",
+		q->value(0).toUInt(),
+		q->value(3).toString().toUtf8().constData(),
+		q->value(2).toString().toUtf8().constData());
+      }
     }
     delete q;