diff --git a/test/src/StreamHelper.php b/test/src/StreamHelper.php
new file mode 100644
index 0000000..cf6e280
--- /dev/null
+++ b/test/src/StreamHelper.php
@@ -0,0 +1,35 @@
+<?php
+
+namespace WellRESTed\Message;
+
+// Declare functions in this namespace so the class under test will use these
+// instead of the internal global functions during testing.
+
+class StreamHelper
+{
+    public static $fail = false;
+}
+
+function fseek($resource, $offset, $whence = SEEK_SET)
+{
+    if (StreamHelper::$fail) {
+        return -1;
+    }
+    return \fseek($resource, $offset, $whence);
+}
+
+function ftell($resource)
+{
+    if (StreamHelper::$fail) {
+        return false;
+    }
+    return \ftell($resource);
+}
+
+function rewind($resource)
+{
+    if (StreamHelper::$fail) {
+        return false;
+    }
+    return \rewind($resource);
+}
\ No newline at end of file
diff --git a/test/tests/unit/Message/StreamTest.php b/test/tests/unit/Message/StreamTest.php
index 714b981..1f57b73 100644
--- a/test/tests/unit/Message/StreamTest.php
+++ b/test/tests/unit/Message/StreamTest.php
@@ -5,8 +5,11 @@ namespace WellRESTed\Test\Unit\Message;
 use InvalidArgumentException;
 use RuntimeException;
 use WellRESTed\Message\Stream;
+use WellRESTed\Message\StreamHelper;
 use WellRESTed\Test\TestCase;
 
+require_once __DIR__ . "/../../../src/StreamHelper.php";
+
 class StreamTest extends TestCase
 {
     private $resource;
@@ -18,6 +21,7 @@ class StreamTest extends TestCase
         $this->resource = fopen("php://memory", "w+");
         $this->resourceDevNull = fopen("/dev/null", "r");
         fwrite($this->resource, $this->content);
+        StreamHelper::$fail = false;
     }
 
     public function tearDown(): void
@@ -106,7 +110,8 @@ class StreamTest extends TestCase
 
     public function testTellThrowsRuntimeExceptionWhenUnableToReadStreamPosition()
     {
-        $stream = new Stream($this->resourceDevNull);
+        StreamHelper::$fail = true;
+        $stream = new Stream($this->resource);
         $this->expectException(RuntimeException::class);
         $stream->tell();
     }
@@ -136,7 +141,8 @@ class StreamTest extends TestCase
 
     public function testSeekThrowsRuntimeExceptionWhenUnableToSeek()
     {
-        $stream = new Stream($this->resourceDevNull);
+        StreamHelper::$fail = true;
+        $stream = new Stream($this->resource);
         $this->expectException(RuntimeException::class);
         $stream->seek(10);
     }
@@ -151,7 +157,8 @@ class StreamTest extends TestCase
 
     public function testRewindThrowsRuntimeExceptionWhenUnableToRewind()
     {
-        $stream = new Stream($this->resourceDevNull);
+        StreamHelper::$fail = true;
+        $stream = new Stream($this->resource);
         $this->expectException(RuntimeException::class);
         $stream->rewind();
     }