diff --git a/fuzz/html.c b/fuzz/html.c
index a2fd1413..e879d879 100644
--- a/fuzz/html.c
+++ b/fuzz/html.c
@@ -16,6 +16,7 @@ LLVMFuzzerInitialize(int *argc ATTRIBUTE_UNUSED,
     xmlInitParser();
 #ifdef LIBXML_CATALOG_ENABLED
     xmlInitializeCatalog();
+    xmlCatalogSetDefaults(XML_CATA_ALLOW_NONE);
 #endif
     xmlSetGenericErrorFunc(NULL, xmlFuzzErrorFunc);
 
diff --git a/fuzz/schema.c b/fuzz/schema.c
index e87670a0..611deeca 100644
--- a/fuzz/schema.c
+++ b/fuzz/schema.c
@@ -15,6 +15,7 @@ LLVMFuzzerInitialize(int *argc ATTRIBUTE_UNUSED,
     xmlInitParser();
 #ifdef LIBXML_CATALOG_ENABLED
     xmlInitializeCatalog();
+    xmlCatalogSetDefaults(XML_CATA_ALLOW_NONE);
 #endif
     xmlSetGenericErrorFunc(NULL, xmlFuzzErrorFunc);
     xmlSetExternalEntityLoader(xmlFuzzEntityLoader);
diff --git a/fuzz/valid.c b/fuzz/valid.c
index 2b8782f4..c5cb43a0 100644
--- a/fuzz/valid.c
+++ b/fuzz/valid.c
@@ -18,6 +18,7 @@ LLVMFuzzerInitialize(int *argc ATTRIBUTE_UNUSED,
     xmlInitParser();
 #ifdef LIBXML_CATALOG_ENABLED
     xmlInitializeCatalog();
+    xmlCatalogSetDefaults(XML_CATA_ALLOW_NONE);
 #endif
     xmlSetGenericErrorFunc(NULL, xmlFuzzErrorFunc);
     xmlSetExternalEntityLoader(xmlFuzzEntityLoader);
diff --git a/fuzz/xinclude.c b/fuzz/xinclude.c
index cd0b564d..cad269b8 100644
--- a/fuzz/xinclude.c
+++ b/fuzz/xinclude.c
@@ -19,6 +19,7 @@ LLVMFuzzerInitialize(int *argc ATTRIBUTE_UNUSED,
     xmlInitParser();
 #ifdef LIBXML_CATALOG_ENABLED
     xmlInitializeCatalog();
+    xmlCatalogSetDefaults(XML_CATA_ALLOW_NONE);
 #endif
     xmlSetGenericErrorFunc(NULL, xmlFuzzErrorFunc);
     xmlSetExternalEntityLoader(xmlFuzzEntityLoader);
diff --git a/fuzz/xml.c b/fuzz/xml.c
index 3955d245..7df8d186 100644
--- a/fuzz/xml.c
+++ b/fuzz/xml.c
@@ -19,6 +19,7 @@ LLVMFuzzerInitialize(int *argc ATTRIBUTE_UNUSED,
     xmlInitParser();
 #ifdef LIBXML_CATALOG_ENABLED
     xmlInitializeCatalog();
+    xmlCatalogSetDefaults(XML_CATA_ALLOW_NONE);
 #endif
     xmlSetGenericErrorFunc(NULL, xmlFuzzErrorFunc);
     xmlSetExternalEntityLoader(xmlFuzzEntityLoader);
diff --git a/fuzz/xpath.c b/fuzz/xpath.c
index f95320bf..3ab60272 100644
--- a/fuzz/xpath.c
+++ b/fuzz/xpath.c
@@ -13,6 +13,10 @@ LLVMFuzzerInitialize(int *argc ATTRIBUTE_UNUSED,
                      char ***argv ATTRIBUTE_UNUSED) {
     xmlFuzzMemSetup();
     xmlInitParser();
+#ifdef LIBXML_CATALOG_ENABLED
+    xmlInitializeCatalog();
+    xmlCatalogSetDefaults(XML_CATA_ALLOW_NONE);
+#endif
     xmlSetGenericErrorFunc(NULL, xmlFuzzErrorFunc);
 
     return 0;
diff --git a/parser.c b/parser.c
index aa5cd841..6c141c06 100644
--- a/parser.c
+++ b/parser.c
@@ -5382,6 +5382,12 @@ xmlParseCatalogPI(xmlParserCtxtPtr ctxt, const xmlChar *catalog) {
 	goto error;
 
     if (URL != NULL) {
+        /*
+         * Unfortunately, the catalog API doesn't report OOM errors.
+         * xmlGetLastError isn't very helpful since we don't know
+         * where the last error came from. We'd have to reset it
+         * before this call and restore it afterwards.
+         */
 	ctxt->catalogs = xmlCatalogAddLocal(ctxt->catalogs, URL);
 	xmlFree(URL);
     }