diff --git a/platform/darwin/src/MGLMultiPoint_Private.h b/platform/darwin/src/MGLMultiPoint_Private.h
index 3da4c0bbb..aa52a02fc 100644
--- a/platform/darwin/src/MGLMultiPoint_Private.h
+++ b/platform/darwin/src/MGLMultiPoint_Private.h
@@ -30,7 +30,7 @@ NS_ASSUME_NONNULL_BEGIN
 @protocol MGLMultiPointDelegate <NSObject>
 
 /** Returns the fill alpha value for the given annotation. */
-- (float)alphaForShapeAnnotation:(MGLShape *)annotation;
+- (double)alphaForShapeAnnotation:(MGLShape *)annotation;
 
 /** Returns the stroke color object for the given annotation. */
 - (mbgl::Color)strokeColorForShapeAnnotation:(MGLShape *)annotation;
@@ -39,7 +39,7 @@ NS_ASSUME_NONNULL_BEGIN
 - (mbgl::Color)fillColorForPolygonAnnotation:(MGLPolygon *)annotation;
 
 /** Returns the stroke width object for the given annotation. */
-- (float)lineWidthForPolylineAnnotation:(MGLPolyline *)annotation;
+- (CGFloat)lineWidthForPolylineAnnotation:(MGLPolyline *)annotation;
 
 @end
 
diff --git a/platform/darwin/src/MGLPolygon.mm b/platform/darwin/src/MGLPolygon.mm
index 3829adf67..b8f02b640 100644
--- a/platform/darwin/src/MGLPolygon.mm
+++ b/platform/darwin/src/MGLPolygon.mm
@@ -44,7 +44,7 @@
     }
 
     mbgl::FillAnnotation annotation { geometry };
-    annotation.opacity = { [delegate alphaForShapeAnnotation:self] };
+    annotation.opacity = { static_cast<float>([delegate alphaForShapeAnnotation:self]) };
     annotation.outlineColor = { [delegate strokeColorForShapeAnnotation:self] };
     annotation.color = { [delegate fillColorForPolygonAnnotation:self] };
 
diff --git a/platform/darwin/src/MGLPolyline.mm b/platform/darwin/src/MGLPolyline.mm
index 9f6f6c354..b81147a3b 100644
--- a/platform/darwin/src/MGLPolyline.mm
+++ b/platform/darwin/src/MGLPolyline.mm
@@ -24,9 +24,9 @@
     }
 
     mbgl::LineAnnotation annotation { geometry };
-    annotation.opacity = { [delegate alphaForShapeAnnotation:self] };
+    annotation.opacity = { static_cast<float>([delegate alphaForShapeAnnotation:self]) };
     annotation.color = { [delegate strokeColorForShapeAnnotation:self] };
-    annotation.width = { [delegate lineWidthForPolylineAnnotation:self] };
+    annotation.width = { static_cast<float>([delegate lineWidthForPolylineAnnotation:self]) };
 
     return annotation;
 }
diff --git a/platform/ios/src/MGLMapView.mm b/platform/ios/src/MGLMapView.mm
index 858ea11a9..28b030b7d 100644
--- a/platform/ios/src/MGLMapView.mm
+++ b/platform/ios/src/MGLMapView.mm
@@ -3033,13 +3033,13 @@ mbgl::Duration MGLDurationInSeconds(NSTimeInterval duration)
     return annotationContext.annotationView;
 }
 
-- (float)alphaForShapeAnnotation:(MGLShape *)annotation
+- (double)alphaForShapeAnnotation:(MGLShape *)annotation
 {
     if (_delegateHasAlphasForShapeAnnotations)
     {
         return [self.delegate mapView:self alphaForShapeAnnotation:annotation];
     }
-    return 1.0f;
+    return 1.0;
 }
 
 - (mbgl::Color)strokeColorForShapeAnnotation:(MGLShape *)annotation
@@ -3058,13 +3058,13 @@ mbgl::Duration MGLDurationInSeconds(NSTimeInterval duration)
     return MGLColorObjectFromUIColor(color);
 }
 
-- (float)lineWidthForPolylineAnnotation:(MGLPolyline *)annotation
+- (CGFloat)lineWidthForPolylineAnnotation:(MGLPolyline *)annotation
 {
     if (_delegateHasLineWidthsForShapeAnnotations)
     {
         return [self.delegate mapView:self lineWidthForPolylineAnnotation:(MGLPolyline *)annotation];
     }
-    return 3.0f;
+    return 3.0;
 }
 
 - (void)installAnnotationImage:(MGLAnnotationImage *)annotationImage
diff --git a/platform/ios/src/MGLMapViewDelegate.h b/platform/ios/src/MGLMapViewDelegate.h
index ed698462c..12a0658a5 100644
--- a/platform/ios/src/MGLMapViewDelegate.h
+++ b/platform/ios/src/MGLMapViewDelegate.h
@@ -247,7 +247,7 @@ NS_ASSUME_NONNULL_BEGIN
  @param annotation The annotation being rendered.
  @return A line width for the polyline, measured in points.
  */
-- (float)mapView:(MGLMapView *)mapView lineWidthForPolylineAnnotation:(MGLPolyline *)annotation;
+- (CGFloat)mapView:(MGLMapView *)mapView lineWidthForPolylineAnnotation:(MGLPolyline *)annotation;
 
 #pragma mark Managing Annotation Views
 
diff --git a/platform/macos/src/MGLMapView.mm b/platform/macos/src/MGLMapView.mm
index 91cd38563..5785f56e0 100644
--- a/platform/macos/src/MGLMapView.mm
+++ b/platform/macos/src/MGLMapView.mm
@@ -2097,11 +2097,11 @@ public:
 
 #pragma mark MGLMultiPointDelegate methods
 
-- (float)alphaForShapeAnnotation:(MGLShape *)annotation {
+- (double)alphaForShapeAnnotation:(MGLShape *)annotation {
     if (_delegateHasAlphasForShapeAnnotations) {
         return [self.delegate mapView:self alphaForShapeAnnotation:annotation];
     }
-    return 1.0f;
+    return 1.0;
 }
 
 - (mbgl::Color)strokeColorForShapeAnnotation:(MGLShape *)annotation {
@@ -2118,11 +2118,11 @@ public:
     return MGLColorObjectFromNSColor(color);
 }
 
-- (float)lineWidthForPolylineAnnotation:(MGLPolyline *)annotation {
+- (CGFloat)lineWidthForPolylineAnnotation:(MGLPolyline *)annotation {
     if (_delegateHasLineWidthsForShapeAnnotations) {
         return [self.delegate mapView:self lineWidthForPolylineAnnotation:(MGLPolyline *)annotation];
     }
-    return 3.0f;
+    return 3.0;
 }
 
 #pragma mark MGLPopoverDelegate methods
diff --git a/platform/macos/src/MGLMapViewDelegate.h b/platform/macos/src/MGLMapViewDelegate.h
index 048cd0b62..6ea69f845 100644
--- a/platform/macos/src/MGLMapViewDelegate.h
+++ b/platform/macos/src/MGLMapViewDelegate.h
@@ -174,7 +174,7 @@ NS_ASSUME_NONNULL_BEGIN
  @param annotation The annotation being rendered.
  @return A line width for the polyline, measured in points.
  */
-- (float)mapView:(MGLMapView *)mapView lineWidthForPolylineAnnotation:(MGLPolyline *)annotation;
+- (CGFloat)mapView:(MGLMapView *)mapView lineWidthForPolylineAnnotation:(MGLPolyline *)annotation;
 
 #pragma mark Selecting Annotations