diff --git a/src/org/netpreserve/jwarc/cdx/CdxFormat.java b/src/org/netpreserve/jwarc/cdx/CdxFormat.java
index 5a5862a..4a54fd6 100644
--- a/src/org/netpreserve/jwarc/cdx/CdxFormat.java
+++ b/src/org/netpreserve/jwarc/cdx/CdxFormat.java
@@ -98,6 +98,7 @@ String formatField(byte fieldName, WarcCaptureRecord record, String filename, lo
             case CHECKSUM:
                 return record.payloadDigest()
                         .map(digestUnchanged ? WarcDigest::raw : WarcDigest::base32)
+                        .map(CdxFormat::escape)
                         .orElse("-");
             case COMPRESSED_ARC_FILE_OFFSET:
                 return position < 0 ? "-" : String.valueOf(position);
@@ -106,7 +107,7 @@ String formatField(byte fieldName, WarcCaptureRecord record, String filename, lo
             case DATE:
                 return CdxFields.DATE_FORMAT.format(record.date());
             case FILENAME:
-                return filename == null ? "-" : filename;
+                return filename == null ? "-" : escape(filename);
             case MIME_TYPE:
                 if (record instanceof WarcRevisit) {
                     return PYWB_REVISIT_MIMETYPE;    
@@ -115,7 +116,7 @@ String formatField(byte fieldName, WarcCaptureRecord record, String filename, lo
                 }                       
             case NORMALIZED_SURT:
                 if (urlkey != null) {
-                    return urlkey;
+                    return escape(urlkey);
                 } else {
                     return escape(URIs.toNormalizedSurt(record.target()));
                 }
@@ -145,7 +146,10 @@ else if (record.contentType().base().equals(MediaType.HTTP)) {
     }
 
     private static String escape(String str) {
-        return str == null ? null : str.replace(" ", "%20");
+        if (str == null) return null;
+        return str.replace(" ", "%20")
+                .replace("\n", "%0A")
+                .replace("\0", "%00");
     }
 
     public static class Builder {
diff --git a/test/org/netpreserve/jwarc/cdx/CdxFormatTest.java b/test/org/netpreserve/jwarc/cdx/CdxFormatTest.java
index 8ac823e..1fa5571 100644
--- a/test/org/netpreserve/jwarc/cdx/CdxFormatTest.java
+++ b/test/org/netpreserve/jwarc/cdx/CdxFormatTest.java
@@ -30,6 +30,26 @@ public void test() throws IOException {
                 CdxFormat.CDX11.format(response, path.getFileName().toString(), 123, 456));
     }
 
+    @Test
+    public void testEscapingSpaces() throws IOException {
+        HttpResponse httpResponse = new HttpResponse.Builder(404, "Not Found")
+                .body(MediaType.HTML, new byte[0])
+                .build();
+        WarcResponse response2 = new WarcResponse.Builder("data:a b")
+                .date(Instant.parse("2022-03-02T21:44:34Z"))
+                .payloadDigest("sha1", "A LNJ7DOPHK477BWWC726H7Y5XBPBNF7")
+                .body(httpResponse)
+                .build();
+        assertEquals("Spaces should be escaped when formatting the urlkey", "a%20b)/",
+                CdxFormat.CDX11.formatField(CdxFields.NORMALIZED_SURT, response2, "foo", 456, 400, null));
+        assertEquals("Spaces should be escaped when formatting the urlkey", "a%20b",
+                CdxFormat.CDX11.formatField(CdxFields.NORMALIZED_SURT, response2, "foo", 456, 400, "a b"));
+        assertEquals("Spaces should be escaped in filename", "a%20b",
+                CdxFormat.CDX11.formatField(CdxFields.FILENAME, response2, "a b", 456, 400, "a b"));
+        assertEquals("Spaces should be escaped in checksum", "A%20LNJ7DOPHK477BWWC726H7Y5XBPBNF7",
+                CdxFormat.CDX11.formatField(CdxFields.CHECKSUM, response2, "a b", 456, 400, "a b"));
+    }
+
     @Test
     public void testDigestUnchanged() throws Exception {
         Path path=Paths.get("/home/jwarc/example.warc.gz");
@@ -94,7 +114,4 @@ public void testFullFilePath() throws Exception {
         assertEquals("org,example)/ 20220302214434 http://example.org/ text/html 404 "+payloadDigest+" - - 456 123 /home/jwarc/example.warc.gz",                      
                 cdxFormat.format(response, path.toAbsolutePath().toString(), 123, 456));
     }
-
-    
-    
 }
\ No newline at end of file