diff --git a/maven-core/src/main/java/org/apache/maven/plugin/version/IntervalUtils.java b/maven-core/src/main/java/org/apache/maven/plugin/version/IntervalUtils.java
index dc91a1476c..66063c8e9d 100644
--- a/maven-core/src/main/java/org/apache/maven/plugin/version/IntervalUtils.java
+++ b/maven-core/src/main/java/org/apache/maven/plugin/version/IntervalUtils.java
@@ -26,7 +26,7 @@ import java.util.regex.Pattern;
 public final class IntervalUtils
 {
     
-    private static final String PERIOD_PART_PATTERN = "[0-9]+[WwDdHhMm]";
+    private static final String PERIOD_PART_PATTERN = "[0-9]+[WwDdHhMm]?";
     
     private static final Map PART_TYPE_CONTRIBUTIONS;
     
@@ -98,7 +98,21 @@ public final class IntervalUtils
     {
         char type = part.charAt( part.length() - 1 );
         
-        int coefficient = Integer.parseInt( part.substring( 0, part.length() -1 ) );
+        String coefficientPart;
+        
+        if( Character.isLetter(type))
+        {
+            coefficientPart = part.substring( 0, part.length() - 1);
+        }
+        else
+        {
+            // if the interval doesn't specify a resolution, assume minutes.
+            coefficientPart = part;
+            
+            type = 'm';
+        }
+        
+        int coefficient = Integer.parseInt( coefficientPart );
         
         Long period = (Long) PART_TYPE_CONTRIBUTIONS.get( "" + Character.toLowerCase( type ) );