diff --git a/Headers/Foundation/NSThread.h b/Headers/Foundation/NSThread.h
index 36e4070da..6a85f66c9 100644
--- a/Headers/Foundation/NSThread.h
+++ b/Headers/Foundation/NSThread.h
@@ -52,7 +52,7 @@ extern "C" {
   NSMutableDictionary	*_thread_dictionary;
   struct autorelease_thread_vars _autorelease_vars;
   id			_gcontext;
-  void                  *_reserved;     // For mfuture expansion
+  void                  *_reserved;     // For future expansion
 }
 
 + (NSThread*) currentThread;
diff --git a/Source/NSThread.m b/Source/NSThread.m
index 2b4c89768..8eb422923 100644
--- a/Source/NSThread.m
+++ b/Source/NSThread.m
@@ -853,27 +853,39 @@ gnustep_base_thread_callback(void)
 
 - (void) start
 {
-  if (_active == NO)
+  if (_active == YES)
     {
-      /* Make sure the notification is posted BEFORE the new thread starts.
-       */
-      gnustep_base_thread_callback();
+      [NSException raise: NSInternalInconsistencyException
+                  format: @"[%@-$@] called on active thread",
+        NSStringFromClass([self class]),
+        NSStringFromSelector(_cmd)];
+    }
+  if (_cancelled == YES)
+    {
+      [NSException raise: NSInternalInconsistencyException
+                  format: @"[%@-$@] called on cancelled thread",
+        NSStringFromClass([self class]),
+        NSStringFromSelector(_cmd)];
+    }
 
-      /* The thread must persist until if finishes executing.
-       */
-      RETAIN(self);
+  /* Make sure the notification is posted BEFORE the new thread starts.
+   */
+  gnustep_base_thread_callback();
 
-      /* Mark the thread as active whiul it's running.
-       */
-      _active = YES;
+  /* The thread must persist until it finishes executing.
+   */
+  RETAIN(self);
 
-      if (objc_thread_detach(@selector(main), self, nil) == NULL)
-        {
-          _active = NO;
-          RELEASE(self);
-          [NSException raise: NSInternalInconsistencyException
-                      format: @"Unable to detach thread (unknown error)"];
-        }
+  /* Mark the thread as active whiul it's running.
+   */
+  _active = YES;
+
+  if (objc_thread_detach(@selector(main), self, nil) == NULL)
+    {
+      _active = NO;
+      RELEASE(self);
+      [NSException raise: NSInternalInconsistencyException
+                  format: @"Unable to detach thread (unknown error)"];
     }
 }
 
diff --git a/Source/NSTimer.m b/Source/NSTimer.m
index ff411f09e..5b9513088 100644
--- a/Source/NSTimer.m
+++ b/Source/NSTimer.m
@@ -196,6 +196,14 @@ static Class	NSDate_class;
     {
       [self invalidate];
     }
+  if (_target != nil)
+    {
+      DESTROY(_target);
+    }
+  if (_info != nil)
+    {
+      DESTROY(_info);
+    }
   RELEASE(_date);
   [super dealloc];
 }
@@ -253,14 +261,6 @@ static Class	NSDate_class;
  */
 - (void) invalidate
 {
-  if (_target != nil)
-    {
-      DESTROY(_target);
-    }
-  if (_info != nil)
-    {
-      DESTROY(_info);
-    }
   /* OPENSTEP allows this method to be called multiple times. */
   //NSAssert(_invalidated == NO, NSInternalInconsistencyException);
   _invalidated = YES;