diff --git a/normalizer/src/main/java/org/biopax/paxtools/normalizer/Resolver.java b/normalizer/src/main/java/org/biopax/paxtools/normalizer/Resolver.java
index 5aee70c4..e1a5109c 100644
--- a/normalizer/src/main/java/org/biopax/paxtools/normalizer/Resolver.java
+++ b/normalizer/src/main/java/org/biopax/paxtools/normalizer/Resolver.java
@@ -101,7 +101,7 @@ protected Resolver() {
    *
    * @param identifier internal identifier used by the data type
    * @param datatype   name, synonym or URI of a data type
-   * @return "true" if the identifier follows the regular expression, "false" otherwise
+   * @return "true" when datatype is recognized, and identifier either matches the pattern or there's no pattern
    */
   public static boolean checkRegExp(String identifier, String datatype) {
     Namespace dt = getNamespace(datatype);
@@ -116,13 +116,8 @@ public static boolean checkRegExp(String identifier, String datatype) {
       identifier = identifier.replaceFirst(banana+dt.getBanana_peel(), "");
     }
 
-    String dtPattern = dt.getPattern();
-    if(StringUtils.isNotBlank(dtPattern)) {
-      return Pattern.compile(dtPattern).matcher(identifier).find();
-    } else {
-      LOG.debug("Cannot check id: {} as regexp is undefined for: {}; return: false", identifier, dt.getPrefix());
-      return false;
-    }
+    //return true when there is no regex pattern defined or the identifier matches
+    return (StringUtils.isNotBlank(dt.getPattern())) ? Pattern.compile(dt.getPattern()).matcher(identifier).find() : true;
   }
 
 
@@ -202,7 +197,7 @@ public static String getURI(String name, String id) {
    */
   public static String getCURIE(String name, String id) {
     Namespace ns = getNamespace(name, true);
-    if (ns != null) {
+    if (ns != null && StringUtils.isNotBlank(ns.getPattern())) {
       if (checkRegExp(id, name)) {
         String prefix = ns.getPrefix();
         //remove "banana" and "peel" prefix from the identifier if any defined and present
diff --git a/normalizer/src/test/java/org/biopax/paxtools/normalizer/ResolverTest.java b/normalizer/src/test/java/org/biopax/paxtools/normalizer/ResolverTest.java
index 3ab1bdab..eedfb5e7 100644
--- a/normalizer/src/test/java/org/biopax/paxtools/normalizer/ResolverTest.java
+++ b/normalizer/src/test/java/org/biopax/paxtools/normalizer/ResolverTest.java
@@ -34,7 +34,8 @@ public final void checkRegExp() {
 				() -> Assertions.assertTrue(Resolver.checkRegExp("MI:0000", MI)), //auto-ignores "MI:"
 				() -> Assertions.assertTrue(Resolver.checkRegExp("0000", MI)),
 				() -> Assertions.assertFalse(Resolver.checkRegExp("0000", "foo")), //no such collection
-				() -> Assertions.assertFalse(Resolver.checkRegExp("0000", "aaindex"))//aaindex no pattern
+				() -> Assertions.assertTrue(Resolver.checkRegExp("0000", "aaindex")),//aaindex no pattern
+				() -> Assertions.assertTrue(Resolver.checkRegExp("98346", "bind"))//no pattern
 		);
 	}