diff --git a/CONTRIBUTORS b/CONTRIBUTORS
index e45c14031..cf6336f70 100644
--- a/CONTRIBUTORS
+++ b/CONTRIBUTORS
@@ -1,5 +1,6 @@
 Amongst other, the following people contributed to ant:
 
+Adam Blinkinsop
 Aleksandr Ishutin
 Alexey Panchenko
 Alexey Solofnenko
diff --git a/contributors.xml b/contributors.xml
index 3c98eca29..160320e83 100644
--- a/contributors.xml
+++ b/contributors.xml
@@ -30,6 +30,10 @@
   <introduction>
   These are some of the many people who have helped Ant become so successful.
   </introduction>
+  <name>
+    <first>Adam</first>
+    <last>Blinkinsop</last>
+  </name>
   <name>
     <first>Aleksandr</first>
     <last>Ishutin</last>
diff --git a/src/main/org/apache/tools/ant/taskdefs/optional/net/RExecTask.java b/src/main/org/apache/tools/ant/taskdefs/optional/net/RExecTask.java
index 0ca112396..a85b0224c 100644
--- a/src/main/org/apache/tools/ant/taskdefs/optional/net/RExecTask.java
+++ b/src/main/org/apache/tools/ant/taskdefs/optional/net/RExecTask.java
@@ -203,14 +203,17 @@ public class RExecTask extends Task {
             InputStream is = this.getInputStream();
             try {
                 StringBuffer sb = new StringBuffer();
+                int windowStart = -s.length();
                 if (timeout == null || timeout.intValue() == 0) {
-                    while (sb.toString().indexOf(s) == -1) {
+                    while (windowStart++ < 0
+                           || !sb.substring(windowStart).equals(s)) {
                         sb.append((char) is.read());
                     }
                 } else {
                     Calendar endTime = Calendar.getInstance();
                     endTime.add(Calendar.SECOND, timeout.intValue());
-                    while (sb.toString().indexOf(s) == -1) {
+                    while (windowStart++ < 0
+                           || !sb.substring(windowStart).equals(s)) {
                         while (Calendar.getInstance().before(endTime)
                             && is.available() == 0) {
                             Thread.sleep(PAUSE_TIME);
diff --git a/src/main/org/apache/tools/ant/taskdefs/optional/net/TelnetTask.java b/src/main/org/apache/tools/ant/taskdefs/optional/net/TelnetTask.java
index 3dea2626e..a982764de 100644
--- a/src/main/org/apache/tools/ant/taskdefs/optional/net/TelnetTask.java
+++ b/src/main/org/apache/tools/ant/taskdefs/optional/net/TelnetTask.java
@@ -340,14 +340,17 @@ public class TelnetTask extends Task {
             InputStream is = this.getInputStream();
             try {
                 StringBuffer sb = new StringBuffer();
+                int windowStart = -s.length();
                 if (timeout == null || timeout.intValue() == 0) {
-                    while (sb.toString().indexOf(s) == -1) {
+                    while (windowStart++ < 0
+                           || !sb.substring(windowStart).equals(s)) {
                         sb.append((char) is.read());
                     }
                 } else {
                     Calendar endTime = Calendar.getInstance();
                     endTime.add(Calendar.SECOND, timeout.intValue());
-                    while (sb.toString().indexOf(s) == -1) {
+                    while (windowStart++ < 0
+                           || !sb.substring(windowStart).equals(s)) {
                         while (Calendar.getInstance().before(endTime)
                                && is.available() == 0) {
                             Thread.sleep(WAIT_INTERVAL);