diff --git a/expat/tests/runtests.c b/expat/tests/runtests.c
index 7fa3e798..600f60b9 100644
--- a/expat/tests/runtests.c
+++ b/expat/tests/runtests.c
@@ -4703,6 +4703,112 @@ START_TEST(test_nsalloc_long_attr)
 #undef MAX_ALLOC_COUNT
 END_TEST
 
+/* Test handling of an attribute name with a long namespace prefix */
+START_TEST(test_nsalloc_long_attr_prefix)
+{
+    const char *text =
+        "<foo:e xmlns:foo='http://example.org/' "
+        /* 64 characters per line */
+        "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789AZ"
+        "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789AZ"
+        "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789AZ"
+        "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789AZ"
+        "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789AZ"
+        "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789AZ"
+        "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789AZ"
+        "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789AZ"
+        "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789AZ"
+        "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789AZ"
+        "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789AZ"
+        "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789AZ"
+        "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789AZ"
+        "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789AZ"
+        "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789AZ"
+        "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789AZ"
+        ":a='12'\n"
+        "xmlns:"
+        /* 64 characters per line */
+        "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789AZ"
+        "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789AZ"
+        "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789AZ"
+        "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789AZ"
+        "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789AZ"
+        "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789AZ"
+        "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789AZ"
+        "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789AZ"
+        "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789AZ"
+        "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789AZ"
+        "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789AZ"
+        "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789AZ"
+        "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789AZ"
+        "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789AZ"
+        "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789AZ"
+        "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789AZ"
+        "='http://example.org/'>"
+        "</foo:e>";
+    const char *elemstr[] = {
+        "http://example.org/ e foo",
+        "http://example.org/ a "
+        "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789AZ"
+        "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789AZ"
+        "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789AZ"
+        "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789AZ"
+        "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789AZ"
+        "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789AZ"
+        "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789AZ"
+        "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789AZ"
+        "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789AZ"
+        "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789AZ"
+        "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789AZ"
+        "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789AZ"
+        "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789AZ"
+        "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789AZ"
+        "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789AZ"
+        "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789AZ"
+    };
+    int i;
+#define MAX_ALLOC_COUNT 15
+    int repeated = 0;
+
+    for (i = 0; i < MAX_ALLOC_COUNT; i++) {
+        /* Repeat some counts to flush out cached allocations */
+        if ((i == 4 && (repeated == 3 || repeated == 6)) ||
+            (i == 7 && repeated == 9) ||
+            (i == 10 && repeated == 12)) {
+            i -= 2;
+            repeated++;
+        }
+        else if ((i == 2 && repeated < 2) ||
+                 (i == 3 &&
+                  (repeated == 2 ||
+                   repeated == 4 ||
+                   repeated == 5 ||
+                   repeated == 7)) ||
+                 (i == 5 && repeated == 8) ||
+                 (i == 6 && repeated == 10) ||
+                 (i == 8 && repeated == 11)) {
+            i--;
+            repeated++;
+        }
+        allocation_count = i;
+        XML_SetReturnNSTriplet(parser, XML_TRUE);
+        XML_SetUserData(parser, elemstr);
+        XML_SetElementHandler(parser,
+                              triplet_start_checker,
+                              triplet_end_checker);
+        if (_XML_Parse_SINGLE_BYTES(parser, text, strlen(text),
+                                    XML_TRUE) != XML_STATUS_ERROR)
+            break;
+        XML_ParserReset(parser, NULL);
+    }
+    if (i == 0)
+        fail("Parsing worked despite failing allocations");
+    else if (i == MAX_ALLOC_COUNT)
+        fail("Parsing failed even at max allocation count");
+}
+#undef MAX_ALLOC_COUNT
+END_TEST
+
 /* Test attribute handling in the face of a dodgy reallocator */
 START_TEST(test_nsalloc_realloc_attributes)
 {
@@ -4879,6 +4985,7 @@ make_suite(void)
     tcase_add_test(tc_nsalloc, test_nsalloc_long_prefix);
     tcase_add_test(tc_nsalloc, test_nsalloc_long_uri);
     tcase_add_test(tc_nsalloc, test_nsalloc_long_attr);
+    tcase_add_test(tc_nsalloc, test_nsalloc_long_attr_prefix);
     tcase_add_test(tc_nsalloc, test_nsalloc_realloc_attributes);
 
     return s;