diff --git a/test/runtests.jl b/test/runtests.jl
index 114b1ad..1916a42 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -16,7 +16,7 @@ end
   @test H_PLANCK ≈ 4.135667696e-15
   @test H_BAR_PLANCK ≈ 6.582119568038699e-16
   @test R_E ≈ 2.8179403205e-15
-  @test R_P ≈ 1.5346982640795807e-12
+  @test R_P ≈ 1.5346982640795807e-18
   @test E_CHARGE ≈ 1
   @test MU_0_VAC ≈ 1.25663706127e-6
   @test EPS_0_VAC ≈ 8.8541878188e-12
@@ -43,4 +43,4 @@ end
   @test chargeof(Species("Cl-")) ≈ -1
   @test chargeof(Species("O--")) ≈ -2
   @test chargeof(Species("N-3")) ≈ -3
-end
\ No newline at end of file
+end