diff --git a/compiler/res/prog8lib/cx16/syslib.p8 b/compiler/res/prog8lib/cx16/syslib.p8
index 45d165df2..c872149dd 100644
--- a/compiler/res/prog8lib/cx16/syslib.p8
+++ b/compiler/res/prog8lib/cx16/syslib.p8
@@ -638,6 +638,9 @@ asmsub  init_system()  {
         and  #%11111000
         ora  P8ZP_SCRATCH_REG
         sta  VERA_DC_VIDEO  ; keep old output mode
+        ldy  #0
+        clc
+        jsr  c64.PLOT   ; force a call to PLOT to avoid autostart black square issue, also see textio.fix_autostart_square()
         lda  #$90       ; black
         jsr  c64.CHROUT
         lda  #1         ; swap fg/bg
diff --git a/compiler/res/prog8lib/cx16/textio.p8 b/compiler/res/prog8lib/cx16/textio.p8
index ce61d7f6f..7b741af40 100644
--- a/compiler/res/prog8lib/cx16/textio.p8
+++ b/compiler/res/prog8lib/cx16/textio.p8
@@ -21,6 +21,23 @@ sub home() {
     txt.chrout(19)
 }
 
+sub fix_autostart_square() {
+    ; Here's a possible work around for weird issue that prints a black character after first call to c64.PLOT()
+    ; if you're also using c64.CINT() yourself. The default prog8 program initialization (which calls CINT) already performs this workaround.
+    ; The problem occurs when a program is autostarded in the emulator with -run -prg test.prg,
+    ; or when the program is saved as AUTOBOOT.X16 and loaded on boot like that.
+    %asm {{
+        sec
+        jsr  c64.PLOT
+        clc
+        jsr  c64.PLOT
+        lda  #' '
+        jsr  c64.CHROUT     ; overwrite the black square
+        clc
+        jmp  c64.PLOT       ; cursor back to original position
+    }}
+}
+
 sub nl() {
     txt.chrout('\n')
 }