Flash memory, the attiny85, and memcpy_P()

I implemented a function into my program for an attiny connected to a display called bpl (boot print line). My goal was to pass simple F("flash strings") to it, like so:

bpl(F("[Boot sequence start]"));

It works fine and all but the String.h library chews up a kb of flash...

uint8_t lines = 0;
static void bpl(String str){
  delay(300);
  if(lines == 7){
    display.clear();
    lines = 0;
  }
  display.printFixed_oldStyle(0,  8 * (lines+1), str.c_str(), STYLE_NORMAL);
  ++lines;
}
//note: the display.printblahblah() function is from lexus2k

so I chose to try a different option;

static void bpl(const __FlashStringHelper* str){
  delay(300);
  if(lines == 7){
    display.clear();
    lines = 0;
  }
  memcpy_P(buf,str,22);
  display.printFixed_oldStyle(0,  8 * (lines+1), buf, STYLE_NORMAL);
  lines++;
}

This method saved a load of flash, but it only executed 2 of the bpls (marked with comments):

void setup() {
  pinMode(1,INPUT);//ran
  display.setFixedFont(ssd1306xled_font6x8);  // ran
  display.begin();//ran
  display.clear();//didnt run
  delay(100);//idk

  bpl(F("[Boot sequence start]"));//ran
  bpl(F("[PIN0 floating      ]"));//ran
  TinyWireM.begin();//idk
  bpl(F("[Wire lib init      ]"));//didnt run
}

What could be done to fix this? am I missing something or did I choose the wrong approach?

Thanks!

EDIT:

static void bpl(const __FlashStringHelper* fstr){
  char buf[strlen_P((PGM_P)fstr)];
  delay(300);
  if(lines == 7){
    display.clear();
    lines = 0;
  }
  strcpy_P(buf,(PGM_P)fstr);
  display.printFixed_oldStyle(0,  8 * (lines+1), buf, STYLE_NORMAL);
  lines++;
}

fixed the issue...