diff --git a/src/libsrc/fiber.pla b/src/libsrc/fiber.pla
index ee95f7a..ff57168 100644
--- a/src/libsrc/fiber.pla
+++ b/src/libsrc/fiber.pla
@@ -46,7 +46,7 @@ byte valstr[] = '0','1','2','3','4','5','6','7','8','9','A','B','C','D','E','F'
 //
 asm fbrSwap(saveVM, restoreVM)
     !SOURCE "vmsrc/plvmzp.inc"
-    HWSP = IPY 
+    HWSP = IPY
     LDA ESTKL,X
     STA SRCL
     LDA ESTKH,X
@@ -66,11 +66,14 @@ asm fbrSwap(saveVM, restoreVM)
     STA ESTK,Y
     DEY
     BPL -
-    TXA
++   TXA
     TAY
 -   LDA $100,Y
     STA (DST),Y
-    LDA (SRC),Y
+    INY
+    BNE -
+    LDY HWSP
+-   LDA (SRC),Y
     STA $100,Y
     INY
     BNE -
@@ -108,7 +111,7 @@ end
 export def fbrInit(numPool)
     byte i
     word pool
-    
+
     if numPool >= MAX_FIBERS
         numPool = MAX_FIBERS
     fin
@@ -144,7 +147,7 @@ end
 //
 export def fbrStop(fid)
     byte i
-    
+
     //
     // Don't STOP fiber 0 (avoid deadlock)
     //
@@ -179,7 +182,7 @@ end
 export def fbrStart(defaddr, param)
     byte i
     word vmstate
-    
+
     for i = fbrMax downto 1
         if fbrState[i] == FIBER_FREE
 	    //
@@ -202,7 +205,7 @@ export def fbrStart(defaddr, param)
 	    // This allows a fiber to return and it will fall into fbrExit
 	    //
             vmstate->hwsp = $FB
-            vmstate=>$FE  = @fbrExit - 1	    
+            vmstate=>$FE  = @fbrExit - 1
             vmstate=>$FC  = defaddr  - 1
 	    //
 	    // Link into RUN list
@@ -222,7 +225,7 @@ end
 //
 export def fbrYield
     byte prev
-    
+
     //
     // Swap to text fiber if this isn't the only fiber RUNning
     //
@@ -237,7 +240,7 @@ end
 //
 export def fbrHalt
     byte i
-     
+
     //
     // Cannot HALT fiber 0 (avoid deadlock)
     //
@@ -284,7 +287,7 @@ end
 
 def fbrTest(fid, param)
     byte i
-    
+
     for i = 1 to param
         puth(fid); putc($0D)
 	fbrYield