diff --git a/src/SignedDistanceFields.jl b/src/SignedDistanceFields.jl
index bd5f664..082069a 100644
--- a/src/SignedDistanceFields.jl
+++ b/src/SignedDistanceFields.jl
@@ -81,4 +81,9 @@ function downsample(img, xsize, ysize=xsize)
     out
 end
 
+if Base.VERSION >= v"1.4.2"
+    include("precompile.jl")
+    _precompile_()
+end
+
 end # module
diff --git a/src/precompile.jl b/src/precompile.jl
new file mode 100644
index 0000000..f911509
--- /dev/null
+++ b/src/precompile.jl
@@ -0,0 +1,6 @@
+function _precompile_()
+    ccall(:jl_generating_output, Cint, ()) == 1 || return nothing
+    @assert precompile(Tuple{typeof(sdf),Matrix{Bool}})   # time: 0.17639625
+    @assert precompile(Tuple{typeof(edf_sq),Matrix{Bool}})   # in case the above doesn't work
+    @assert precompile(Tuple{typeof(downsample),Matrix{Float64},Int})   # time: 0.0495947
+end