diff --git a/src/writer.jl b/src/writer.jl
index 1966a06..bdbabcf 100644
--- a/src/writer.jl
+++ b/src/writer.jl
@@ -121,7 +121,7 @@ function write(path::AbstractString, o::Writer; force=false)
     # Detect the shape type code from the first available geometry
     # There can only be one shape type in the file.
     # If all values are missing, the shape type is Missing
-    if iterate(skipmissing(geoms)) == nothing
+    if isnothing(iterate(skipmissing(geoms)))
         trait = Missing
         hasz = hasm = false
     else
@@ -295,7 +295,7 @@ function _write(io::IO, trait::GI.AbstractGeometryTrait, geom; kw...)
     end
     # write x/y part of points
     for point in GI.getpoint(geom)
-        x, y = GI.x(point), GI.y(point)
+        x, y = Float64(GI.x(point)), Float64(GI.y(point))
         bytes += Base.write(io, x)
         bytes += Base.write(io, y)
     end
@@ -334,7 +334,7 @@ function _calc_mbr(geom)
     low_x = low_y = Inf
     high_x = high_y = -Inf
     for point in GI.getpoint(geom)
-        x, y = GI.x(point), GI.y(point)
+        x, y = Float64(GI.x(point)), Float64(GI.y(point))
         low_x = min(low_x, x)
         high_x = max(high_x, x)
         low_y = min(low_y, y)
@@ -350,14 +350,14 @@ function _write_others(io, geom;
     bytes = 0
     # TODO what to do when hasm == false but hasz == true
     if hasz
-        b, zrange = _write_others(GI.z, io, geom)
+        b, zrange = _write_others(p -> Float64(GI.z(p)), io, geom)
         bytes += b
     else
         zrange = Interval(0.0, 0.0)
     end
 
     if hasm
-        b, mrange = _write_others(GI.m, io, geom)
+        b, mrange = _write_others(p -> Float64(GI.m(p)), io, geom)
         bytes += b
     else
         mrange = Interval(0.0, 0.0)
diff --git a/test/writer.jl b/test/writer.jl
index ea19da8..5c49a62 100644
--- a/test/writer.jl
+++ b/test/writer.jl
@@ -34,6 +34,39 @@
         t = Shapefile.Table(file)
         @test only(t.geometry) == Polygon(box, [0], ps)
 
+        # Float32 coordinates
+        struct Point32
+            x::Float32
+            y::Float32
+        end
+
+        struct LineString32
+            points::Vector{Point32}
+        end
+
+        # basic GI interface implementation
+        GI.isgeometry(::Type{Point32}) = true
+        GI.geomtrait(::Point32) = GI.PointTrait()
+        GI.ncoord(::GI.PointTrait, p::Point32) = 2
+        GI.getcoord(::GI.PointTrait, p::Point32, i) = getfield(p, i)
+
+        GI.isgeometry(::Type{LineString32}) = true
+        GI.geomtrait(::LineString32) = GI.LineStringTrait()
+        GI.ncoord(::GI.LineStringTrait, p::LineString32) = 2
+        GI.ngeom(::GI.LineStringTrait, l::LineString32) = length(l.points)
+        GI.getgeom(::GI.LineStringTrait, l::LineString32, i) = getindex(l.points, i)
+
+        file = tempname()
+        Shapefile.write(file, Point32(0, 0))
+        t = Shapefile.Table(file)
+        @test only(t.geometry) == Point(0, 0)
+
+        file = tempname()
+        geom = LineString32([Point32(0, 0), Point32(1, 0), Point32(1, 1), Point32(0, 1)])
+        Shapefile.write(file, geom)
+        t = Shapefile.Table(file)
+        @test only(t.geometry) == Polyline(Rect(0, 0, 1, 1), [0], [Point(0, 0), Point(1, 0), Point(1, 1), Point(0, 1)])
+
         # feature
         struct F end
         GI.trait(::F) = GI.FeatureCollectionTrait()