diff --git a/common/src/test/java/com/cldellow/manu/common/IntVectorTest.java b/common/src/test/java/com/cldellow/manu/common/IntVectorTest.java
index bc3494c..e19e298 100644
--- a/common/src/test/java/com/cldellow/manu/common/IntVectorTest.java
+++ b/common/src/test/java/com/cldellow/manu/common/IntVectorTest.java
@@ -62,8 +62,8 @@ public void testVectorSetOOBE() {
     }
 
     @Property
-    public void testLikeArray(int[] ints) {
-        IntVector iv = new IntVector();
+    public void testLikeArray(int[] ints, boolean grow) {
+        IntVector iv = grow ? new IntVector(1) : new IntVector();
         for (int i = 0; i < ints.length; i++) {
             assertEquals(i, iv.getSize());
             iv.add(ints[i]);
diff --git a/format/src/test/java/com/cldellow/manu/format/LengthOpsTest.java b/format/src/test/java/com/cldellow/manu/format/LengthOpsTest.java
index da168be..70c8c55 100644
--- a/format/src/test/java/com/cldellow/manu/format/LengthOpsTest.java
+++ b/format/src/test/java/com/cldellow/manu/format/LengthOpsTest.java
@@ -53,7 +53,15 @@ public void encodeTooSmallLen(@InRange(max = "-1") int len) {
 
 
     @Property
-    public void decodeIdAnyLen(@InRange(min = "0", max = "63") int id, @InRange(min = "0") int len) {
+    public void decodeIdAnyLen(@InRange(min = "0", max = "63") int id, @InRange(min = "0", max = "254") int smallLen, @InRange(min = "255", max = "65534") int mediumLen,  @InRange(min = "65535") int largeLen,  @InRange(min = "0", max = "2") int lenSelect) {
+        int len;
+
+        switch (lenSelect) {
+            case 2: len = largeLen;  break;
+            case 1: len = mediumLen; break;
+            case 0: len = smallLen;  break;
+            default: throw new Error("Dead code");
+        }
         byte encoded = LengthOps.encode((byte) id, len);
         assertEquals(id, LengthOps.decodeId(encoded));
 
diff --git a/format/src/test/java/com/cldellow/manu/format/ReaderTest.java b/format/src/test/java/com/cldellow/manu/format/ReaderTest.java
index 982d9f0..990f9ad 100644
--- a/format/src/test/java/com/cldellow/manu/format/ReaderTest.java
+++ b/format/src/test/java/com/cldellow/manu/format/ReaderTest.java
@@ -2,8 +2,10 @@
 
 import com.cldellow.manu.common.Common;
 import com.pholser.junit.quickcheck.Property;
+import com.pholser.junit.quickcheck.generator.InRange;
 import com.pholser.junit.quickcheck.generator.Size;
 import com.pholser.junit.quickcheck.runner.JUnitQuickcheck;
+import junit.framework.AssertionFailedError;
 import org.junit.After;
 import org.junit.Test;
 import org.junit.runner.RunWith;
@@ -143,14 +145,47 @@ public void testSparseRecordsIterator() throws Exception {
         }
     }
 
+    private void testVariableSizes(int[] f1, int[] f2, int[] f3, int[] f4, int encoder) throws Exception {
+        FieldEncoder e;
+        switch (encoder) {
+            case 0:
+                e = new CopyEncoder();
+                break;
+            case 1:
+                e = new PFOREncoder();
+                break;
+            case 2:
+                e = new SingleValueEncoder();
+                f1 = new int[] { f1[0] };
+                f2 = new int[] { f2[0] };
+                f3 = new int[] { f3[0] };
+                f4 = new int[] { f4[0] };
+                break;
+            case 3:
+                e = new AverageEncoder();
+                for (int i = 1 ; i < f1.length ; i++) {
+                    f1[i] = f1[0];
+                    f2[i] = f2[0];
+                    f3[i] = f3[0];
+                    f4[i] = f4[0];
+                }
+            break;
+            default:
+                throw new Error();
+        }
+
+        testVariableSize(f1, f2, f3, f4, e);
+    }
+
     @Property(trials = 5)
     public void testVariableSize512(
             int @Size(min = 512, max = 512) [] f1,
             int @Size(min = 512, max = 512) [] f2,
             int @Size(min = 512, max = 512) [] f3,
-            int @Size(min = 512, max = 512) [] f4
+            int @Size(min = 512, max = 512) [] f4,
+            @InRange(min="0", max="3") int encoder
     ) throws Exception {
-        testVariableSize(f1, f2, f3, f4);
+        testVariableSizes(f1, f2, f3, f4, encoder);
     }
 
     @Property(trials = 5)
@@ -158,9 +193,10 @@ public void testVariableSize20K(
             int @Size(min = 20480, max = 20480) [] f1,
             int @Size(min = 20480, max = 20480) [] f2,
             int @Size(min = 20480, max = 20480) [] f3,
-            int @Size(min = 20480, max = 20480) [] f4
+            int @Size(min = 20480, max = 20480) [] f4,
+            @InRange(min="0", max="2") int encoder
     ) throws Exception {
-        testVariableSize(f1, f2, f3, f4);
+        testVariableSizes(f1, f2, f3, f4, encoder);
     }
 
     @Test
@@ -188,6 +224,11 @@ void testVariableSize(int[] f1, int[] f2, int[] f3, int[] f4) throws Exception {
         FieldEncoder encoder = new CopyEncoder();
         if (f1.length == 1)
             encoder = new AverageEncoder();
+
+        testVariableSize(f1, f2, f3, f4, encoder);
+    }
+
+    void testVariableSize(int[] f1, int[] f2, int[] f3, int[] f4, FieldEncoder encoder) throws Exception {
         int[][] values1 = new int[][]{f1, f2};
         SimpleRecord r1 = new SimpleRecord(1, new FieldEncoder[]{encoder, encoder}, values1);