diff --git a/src/external.jl b/src/external.jl
index 45311a7..b124706 100644
--- a/src/external.jl
+++ b/src/external.jl
@@ -18,7 +18,9 @@ mutable struct FixExternal
         API.lammps_set_fix_external_callback(lmp, name, callback, ctx)
 
         # Ensure function is compiled before timestep 0
-        @assert precompile(this.callback, (FixExternal, Int, Int, Int, Vector{Int32}, Matrix{Float64}, Matrix{Float64}))
+        if !precompile(this.callback, (FixExternal, Int, Int, Int, Vector{Int32}, Matrix{Float64}, Matrix{Float64}))
+            @warn "Failed to precompile the callback" this.callback
+        end
         return this
     end
 end
diff --git a/test/runtests.jl b/test/runtests.jl
index 471e090..650015e 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -59,7 +59,7 @@ LMP(["-screen", "none"]) do lmp
     command(lmp, "region cell block 0 1 0 1 0 1 units box")
     command(lmp, "create_box 1 cell")
     command(lmp, "fix julia all external pf/callback 1 1")
-    LAMMPS.FixExternal(lmp, "julia") do fix, timestep, nlocal, ids, x, fexternal
+    LAMMPS.FixExternal(lmp, "julia") do fix, timestep, nlocal, nghost, ids, x, fexternal
        LAMMPS.energy_global!(fix, 0.0)
        called[] = true
     end