diff --git a/terminal/src/main/java/org/jline/utils/AttributedStringBuilder.java b/terminal/src/main/java/org/jline/utils/AttributedStringBuilder.java
index 9f41892bb..e7bb11d48 100644
--- a/terminal/src/main/java/org/jline/utils/AttributedStringBuilder.java
+++ b/terminal/src/main/java/org/jline/utils/AttributedStringBuilder.java
@@ -26,6 +26,7 @@ public class AttributedStringBuilder extends AttributedCharSequence implements A
     private int[] style;
     private int length;
     private int tabs = 0;
+    private int lastLineLength = 0;
     private AttributedStyle current = AttributedStyle.DEFAULT;
 
     public static AttributedString append(CharSequence... strings) {
@@ -157,6 +158,11 @@ public AttributedStringBuilder append(AttributedCharSequence str, int start, int
                 ensureCapacity(length + 1);
                 buffer[length] = c;
                 style[length] = s;
+                if (c == '\n') {
+                    lastLineLength = 0;
+                } else {
+                    lastLineLength++;
+                }
                 length++;
             }
         }
@@ -333,6 +339,11 @@ public AttributedStringBuilder ansiAppend(String ansi) {
                 ensureCapacity(length + 1);
                 buffer[length] = c;
                 style[length] = this.current.getStyle();
+                if (c == '\n') {
+                    lastLineLength = 0;
+                } else {
+                    lastLineLength++;
+                }
                 length++;
             }
         }
@@ -340,21 +351,36 @@ public AttributedStringBuilder ansiAppend(String ansi) {
     }
 
     protected void insertTab(AttributedStyle s) {
-        int nb = tabs - length % tabs;
+        int nb = tabs - lastLineLength % tabs;
         ensureCapacity(length + nb);
         for (int i = 0; i < nb; i++) {
             buffer[length] = ' ';
             style[length] = s.getStyle();
             length++;
         }
+        lastLineLength += nb;
     }
 
     public void setLength(int l) {
         length = l;
     }
 
-    public AttributedStringBuilder tabs(int tabs) {
-        this.tabs = tabs;
+    /**
+     * Set the number of spaces a tab is expanded to. Tab size cannot be changed
+     * after text has been added to prevent inconsistent indentation.
+     *
+     * If tab size is set to 0, tabs are not expanded (the default).
+     * @param tabsize Spaces per tab or 0 for no tab expansion. Must be non-negative
+     * @return
+     */
+    public AttributedStringBuilder tabs(int tabsize) {
+        if (length > 0) {
+            throw new IllegalStateException("Cannot change tab size after appending text");
+        }
+        if (tabsize < 0) {
+            throw new IllegalArgumentException("Tab size must be non negative");
+        }
+        this.tabs = tabsize;
         return this;
     }
 
diff --git a/terminal/src/test/java/org/jline/utils/AttributedStringBuilderTest.java b/terminal/src/test/java/org/jline/utils/AttributedStringBuilderTest.java
new file mode 100644
index 000000000..0d137f7e6
--- /dev/null
+++ b/terminal/src/test/java/org/jline/utils/AttributedStringBuilderTest.java
@@ -0,0 +1,105 @@
+package org.jline.utils;
+
+import org.junit.Test;
+
+import static org.junit.Assert.*;
+
+public class AttributedStringBuilderTest {
+	private static String TAB_SIZE_ERR_MSG = "Incorrect tab size";
+
+	/**
+	 * Test single line with tabs in
+	 */
+    @Test
+    public void testTabSize() {
+        AttributedStringBuilder sb;
+        sb = new AttributedStringBuilder().tabs(4);
+        sb.append("hello\tWorld");
+        assertEquals(TAB_SIZE_ERR_MSG, "hello   World", sb.toString());
+
+        sb = new AttributedStringBuilder().tabs(5);
+        sb.append("hello\tWorld");
+        assertEquals(TAB_SIZE_ERR_MSG, "hello     World", sb.toString());
+    }
+
+    /**
+     * Test multiple lines with tabs in
+     */
+    @Test
+    public void testSplitLineTabSize() {
+       AttributedStringBuilder sb;
+       sb = new AttributedStringBuilder().tabs(4);
+       sb.append("hello\n\tWorld");
+       assertEquals(TAB_SIZE_ERR_MSG, "hello\n    World", sb.toString());
+
+       sb = new AttributedStringBuilder().tabs(4);
+       sb.append("hello\tWorld\n\tfoo\tbar");
+       assertEquals(TAB_SIZE_ERR_MSG, "hello   World\n    foo bar", sb.toString());
+
+       sb = new AttributedStringBuilder().tabs(5);
+       sb.append("hello\n\tWorld");
+       assertEquals(TAB_SIZE_ERR_MSG, "hello\n     World", sb.toString());
+
+       sb = new AttributedStringBuilder().tabs(5);
+       sb.append("hello\tWorld\n\tfoo\tbar");
+       assertEquals(TAB_SIZE_ERR_MSG, "hello     World\n     foo  bar", sb.toString());
+    }
+
+    @Test
+    public void testAppendToString() {
+        AttributedStringBuilder sb;
+        String expected = "";
+        sb = new AttributedStringBuilder().tabs(4);
+
+        sb.append("hello"); expected += "hello";
+        sb.append("\tWorld"); expected += "   World"; //append to first line
+        assertEquals(TAB_SIZE_ERR_MSG, expected, sb.toString());
+
+        sb.append("\nfoo\tbar"); expected += "\nfoo bar"; //append new line
+        assertEquals(TAB_SIZE_ERR_MSG, expected, sb.toString());
+
+        sb.append("lorem\tipsum"); expected += "lorem    ipsum"; //append to second line
+        assertEquals(TAB_SIZE_ERR_MSG, expected, sb.toString());
+    }
+
+    @Test
+    public void testFromAnsiWithTabs() {
+        AttributedStringBuilder sb;
+        String expected = "";
+        sb = new AttributedStringBuilder().tabs(4);
+
+        sb.appendAnsi("hello\tWorld"); expected += "hello   World";
+        assertEquals(TAB_SIZE_ERR_MSG, expected, sb.toString());
+
+        sb.appendAnsi("\033[38;5;120mgreen\tfoo\033[39m"); expected += "green  foo";
+        assertEquals(TAB_SIZE_ERR_MSG, expected, sb.toString());
+        sb.appendAnsi("\n\033[38;5;120mbar\tbaz\033[39m"); expected += "\nbar baz";
+        assertEquals(TAB_SIZE_ERR_MSG, expected, sb.toString());
+    }
+
+    /**
+     * Test that tabs are not expanded in strings if tab size has not been set
+     */
+    @Test
+    public void testUnsetTabSize() {
+        AttributedStringBuilder sb;
+        String expected = "";
+        sb = new AttributedStringBuilder();
+
+        sb.append("hello\tWorld"); expected += "hello\tWorld";
+        assertEquals(TAB_SIZE_ERR_MSG, expected, sb.toString());
+    }
+
+    @Test(expected=IllegalStateException.class)
+    public void testChangingExistingTabSize() throws Exception {
+        AttributedStringBuilder sb = new AttributedStringBuilder();
+        sb.append("helloWorld");
+        sb.tabs(4);
+    }
+
+    @Test(expected=IllegalArgumentException.class)
+    public void testNegativeTabSize() throws Exception {
+        @SuppressWarnings("unused")
+        AttributedStringBuilder sb = new AttributedStringBuilder().tabs(-1);
+    }
+}