diff --git a/macros/GTE.Macs.s b/macros/GTE.Macs.s
index e1cfcaa..4313f90 100644
--- a/macros/GTE.Macs.s
+++ b/macros/GTE.Macs.s
@@ -146,6 +146,7 @@ PAD_KEY_DOWN           equ   $0400
 ENGINE_MODE_TWO_LAYER  equ   $0001
 ENGINE_MODE_DYN_TILES  equ   $0002
 ENGINE_MODE_BNK0_BUFF  equ   $0004
+ENGINE_MODE_USER_TOOL  equ   $8000       ; Communicate if GTE is loaded as a system tool, or a user tool
 
 ; Render flags
 RENDER_ALT_BG1         equ   $0001
diff --git a/src/Defs.s b/src/Defs.s
index 48f8d37..9457df8 100644
--- a/src/Defs.s
+++ b/src/Defs.s
@@ -166,6 +166,7 @@ SPRITE_VBUFF_PTR        equ  224         ; 32 bytes of adjusted pointers to VBuf
 ENGINE_MODE_TWO_LAYER  equ   $0001
 ENGINE_MODE_DYN_TILES  equ   $0002
 ENGINE_MODE_BNK0_BUFF  equ   $0004
+ENGINE_MODE_USER_TOOL  equ   $8000       ; Communicate if GTE is loaded as a system tool, or a user tool
 
 ; Render flags
 RENDER_ALT_BG1         equ   $0001
diff --git a/src/Tool.s b/src/Tool.s
index 760331e..dae5db3 100644
--- a/src/Tool.s
+++ b/src/Tool.s
@@ -156,7 +156,9 @@ zpToUse         =    userId+4
 
 ; SetWAP(userOrSystem, tsNum, waptPtr)
 
-                pea     #$8000             ; $8000 = user tool set
+                lda     EngineMode         ; $0000 = system tool, $8000 = user tool set
+                and     #$8000
+                pha
                 pei     ToolNum            ; Push the tool number from the direct page
                 pea     $0000              ; High word of WAP is zero (bank 0)
                 phd                        ; Low word of WAP is the direct page