diff --git a/src/OLEDDisplay.cpp b/src/OLEDDisplay.cpp
index 409c97a..5dd0398 100644
--- a/src/OLEDDisplay.cpp
+++ b/src/OLEDDisplay.cpp
@@ -1080,3 +1080,54 @@ void OLEDDisplay::drawRoundRect(int16_t x, int16_t y, int16_t w, int16_t h, int1
   drawCircleQuads(x+w-r-1, y+h-r-1, r, 8);
   drawCircleQuads(x+r    , y+h-r-1, r, 4);
 }
+
+/**************************************************************************/
+/*!
+    @brief  Quarter-circle drawer with fill, used for circles and roundrects
+    @param  x0       Center-point x coordinate
+    @param  y0       Center-point y coordinate
+    @param  r        Radius of circle
+    @param  corners  Mask bits indicating which quarters we're doing
+    @param  delta    Offset from center-point, used for round-rects
+    @param  color    16-bit 5-6-5 Color to fill with
+*/
+/**************************************************************************/
+void OLEDDisplay::fillCircleHelper(int16_t x0, int16_t y0, int16_t r,
+                                    uint8_t corners, int16_t delta) {
+  int16_t f = 1 - r;
+  int16_t ddF_x = 1;
+  int16_t ddF_y = -2 * r;
+  int16_t x = 0;
+  int16_t y = r;
+  int16_t px = x;
+  int16_t py = y;
+
+  delta++; // Avoid some +1's in the loop
+
+  while (x < y) {
+    if (f >= 0) {
+      y--;
+      ddF_y += 2;
+      f += ddF_y;
+    }
+    x++;
+    ddF_x += 2;
+    f += ddF_x;
+    // These checks avoid double-drawing certain lines, important
+    // for the SSD1306 library which has an INVERT drawing mode.
+    if (x < (y + 1)) {
+      if (corners & 1)
+        drawVerticalLine(x0 + x, y0 - y, 2 * y + delta);
+      if (corners & 2)
+        drawVerticalLine(x0 - x, y0 - y, 2 * y + delta);
+    }
+    if (y != py) {
+      if (corners & 1)
+        drawVerticalLine(x0 + py, y0 - px, 2 * px + delta);
+      if (corners & 2)
+        drawVerticalLine(x0 - py, y0 - px, 2 * px + delta);
+      py = y;
+    }
+    px = x;
+  }
+}