diff --git a/Core/src/org/sleuthkit/autopsy/modules/interestingitems/Bundle.properties-MERGED b/Core/src/org/sleuthkit/autopsy/modules/interestingitems/Bundle.properties-MERGED
index 7ca4901b1b..a1b97a0f54 100755
--- a/Core/src/org/sleuthkit/autopsy/modules/interestingitems/Bundle.properties-MERGED
+++ b/Core/src/org/sleuthkit/autopsy/modules/interestingitems/Bundle.properties-MERGED
@@ -37,6 +37,8 @@ FilesSetPanel.ingest.createNewFilter=Create/edit file ingest filters...
 FilesSetPanel.ingest.messages.filtersMustBeNamed=File ingest filters must be named.
 FilesSetPanel.rule.title=File Filter Rule
 FilesSetRulePanel.bytes=Bytes
+#{0} - regex
+FilesSetRulePanel.CommaInRegexWarning=Warning: Comma(s) in the file extension field will be interpreted as part of a regex and will not split the entry into multiple extensions (Entered: "{0}")
 FilesSetRulePanel.DaysIncludedEmptyError=Number of days included cannot be empty.
 FilesSetRulePanel.DaysIncludedInvalidError=Number of days included must be a positive integer.
 FilesSetRulePanel.gigaBytes=Gigabytes
diff --git a/Core/src/org/sleuthkit/autopsy/modules/interestingitems/FilesSetRulePanel.java b/Core/src/org/sleuthkit/autopsy/modules/interestingitems/FilesSetRulePanel.java
index 9744b0c5bf..12339b54f6 100644
--- a/Core/src/org/sleuthkit/autopsy/modules/interestingitems/FilesSetRulePanel.java
+++ b/Core/src/org/sleuthkit/autopsy/modules/interestingitems/FilesSetRulePanel.java
@@ -57,7 +57,9 @@ final class FilesSetRulePanel extends javax.swing.JPanel {
         "FilesSetRulePanel.NoPathError=Path cannot be empty",
         "FilesSetRulePanel.DaysIncludedEmptyError=Number of days included cannot be empty.",
         "FilesSetRulePanel.DaysIncludedInvalidError=Number of days included must be a positive integer.",
-        "FilesSetRulePanel.ZeroFileSizeError=File size condition value must not be 0 (Unless = is selected)."
+        "FilesSetRulePanel.ZeroFileSizeError=File size condition value must not be 0 (Unless = is selected).",
+        "#{0} - regex",
+        "FilesSetRulePanel.CommaInRegexWarning=Warning: Comma(s) in the file extension field will be interpreted as part of a regex and will not split the entry into multiple extensions (Entered: \"{0}\")",
     })
 
     private static final long serialVersionUID = 1L;
@@ -358,6 +360,16 @@ final class FilesSetRulePanel extends javax.swing.JPanel {
                 return false;
             }
             if (this.nameRegexCheckbox.isSelected()) {
+                
+                // If extension is also selected and the regex contains a comma, display a warning
+                // since it is unclear whether the comma is part of a regex or is separating extensions.
+                if (this.extensionRadioButton.isSelected() && this.nameTextField.getText().contains(",")) {
+                    NotifyDescriptor notifyDesc = new NotifyDescriptor.Message(
+                            Bundle.FilesSetRulePanel_CommaInRegexWarning(this.nameTextField.getText()),
+                            NotifyDescriptor.WARNING_MESSAGE);
+                    DialogDisplayer.getDefault().notify(notifyDesc);
+                }
+                
                 try {
                     Pattern.compile(this.nameTextField.getText());
                 } catch (PatternSyntaxException ex) {