diff --git a/js/kiri-driver-fdm.js b/js/kiri-driver-fdm.js
index 5260f4ac..7a07a893 100644
--- a/js/kiri-driver-fdm.js
+++ b/js/kiri-driver-fdm.js
@@ -49,7 +49,7 @@ var gs_kiri_fdm = exports;
             doSolidLayers = solidLayers && !vaseMode,
             firstOffset = sdev.nozzleSize / 2,
             shellOffset = sdev.nozzleSize * spro.sliceShellSpacing,
-            fillOffset = shellOffset * settings.synth.fillOffsetMult,
+            fillOffset = sdev.nozzleSize * settings.synth.fillOffsetMult,
             fillSpacing = sdev.nozzleSize,
             sliceFillAngle = spro.sliceFillAngle,
             view = widget.mesh && widget.mesh.newGroup ? widget.mesh.newGroup() : null;
diff --git a/js/kiri-fill.js b/js/kiri-fill.js
index b7a37895..4f7986a0 100644
--- a/js/kiri-fill.js
+++ b/js/kiri-fill.js
@@ -33,7 +33,7 @@ var gs_kiri_fill = exports;
      */
     function fillHex(target, full) {
         // compute segment lengths (vert/horiz and 45)
-        let spacing = target.offset() / 2;
+        let spacing = target.offset();
         let vhlen = (1 - target.density()) * 4 + spacing;
         let anxlen = ROUND(Math.cos(30 * DEG2RAD) * vhlen, 7);
         let anylen = ROUND(Math.sin(30 * DEG2RAD) * vhlen, 7);
@@ -126,7 +126,7 @@ var gs_kiri_fill = exports;
         let span_x = bounds.max.x - bounds.min.x;
         let span_y = bounds.max.y - bounds.min.y;
         let density = target.density();
-        let offset = target.offset();
+        let offset = target.offset() / 2;
         let tile = 1 + (1 - density) * 3;
         let tile_x = tile + offset;
         let tile_xc = span_x / tile_x;
@@ -177,14 +177,11 @@ var gs_kiri_fill = exports;
         }
 
         for (let tx=0; tx<=tile_xc; tx++) {
+            let bx = tx * tile_x + bounds.min.x;
+            let xp = bx + tile_x - line_w/2 - offset/2;
             target.newline();
-            for (let ty=0; ty<=tile_yc; ty++) {
-                let bx = tx * tile_x + bounds.min.x;
-                let by = ty * tile + bounds.min.y;
-                let xp = bx + tile_x - line_w/2 - offset/2;
-                target.emit(xp, by);
-                target.emit(xp, by + tile);
-            }
+            target.emit(xp, bounds.min.y);
+            target.emit(xp, bounds.max.y);
         }
     }
 
diff --git a/js/kiri.js b/js/kiri.js
index 0035e16d..f57b3982 100644
--- a/js/kiri.js
+++ b/js/kiri.js
@@ -2506,7 +2506,7 @@ self.kiri.license = exports.LICENSE;
             sliceFillType: UC.newSelectField("type", {modes:FDM}, "infill"),
             sliceFillSparse: UC.newInput("percentage", {title:"for infill areas\n0.0 - 1.0", convert:UC.toFloat, bound:UC.bound(0.0,1.0), modes:FDM}),
             sliceFillAngle: UC.newInput("solid angle", {title:"base angle in degrees", convert:UC.toFloat, modes:FDM}),
-            sliceFillOverlap: UC.newInput("shell overlap", {title:"overlap with shell\nas % of nozzle width\nhigher bonds better\n0.0 - 1.0", convert:UC.toFloat, bound:UC.bound(0.0,2.0), modes:FDM}),
+            sliceFillOverlap: UC.newInput("overlap", {title:"overlap with shell and fill\nas % of nozzle width\nhigher bonds better\n0.0 - 1.0", convert:UC.toFloat, bound:UC.bound(0.0,2.0), modes:FDM}),
 
             // laser
             laserOffset: UC.newInput("cut offset", {title:"millimeters\nadjust for beam width", convert:UC.toFloat, modes:LASER}),