diff --git a/arbor/fvm_layout.cpp b/arbor/fvm_layout.cpp
index aa8ba5f57..e8baafef9 100644
--- a/arbor/fvm_layout.cpp
+++ b/arbor/fvm_layout.cpp
@@ -397,8 +397,8 @@ fvm_cv_discretize(const cable_cell& cell,
             // Compute
             auto len = embedding.integrate_length(span);
             for (auto& [ion, info]: diffusive_ions) {
-                // TODO scale to m^2/s (now at 1e-7*m^2/s)
-                auto sigma = len/embedding.integrate_ixa(span, info.axial_resistivity[0].at(bid));
+                // TODO scale to m^2/s
+                auto sigma = 1e7*len/embedding.integrate_ixa(span, info.axial_resistivity[0].at(bid));
                 info.face_diffusivity[i] = sigma;
             }
         }
diff --git a/doc/concepts/decor.rst b/doc/concepts/decor.rst
index 736dcfccb..6605a91a1 100644
--- a/doc/concepts/decor.rst
+++ b/doc/concepts/decor.rst
@@ -231,11 +231,11 @@ can't be overridden at cell or region level.
 
 Each ion species has the following properties:
 
-1. *internal concentration*: concentration on interior of the membrane [mM].
-2. *external concentration*: concentration on exterior of the membrane [mM].
+1. *internal concentration*: concentration on interior of the membrane :math:`[mM]`.
+2. *external concentration*: concentration on exterior of the membrane :math:`[mM]`.
 3. *reversal potential*: reversal potential [mV].
 4. *reversal potential mechanism*:  method for calculating reversal potential.
-5. *diffusivity*: diffusion coefficient for marker concentration, defaults to zero (unit is currently [10^-7 m^2/s], which will be adapted in the future).
+5. *diffusivity*: diffusion coefficient for marker concentration, defaults to zero :math:`[m^2/s]`.
 
 Properties 1, 2 and 3 must be defined, and are used as the initial values for
 each quantity at the start of the simulation. They are specified globally,
diff --git a/test/unit/test_diffusion.cpp b/test/unit/test_diffusion.cpp
index 4d2f75544..ce0570122 100644
--- a/test/unit/test_diffusion.cpp
+++ b/test/unit/test_diffusion.cpp
@@ -150,7 +150,7 @@ TEST(diffusion, errors) {
 
 TEST(diffusion, by_initial_concentration) {
     auto rec = linear{30, 3, 6}
-        .set_diffusivity(0.005)
+        .set_diffusivity(5e-10)
         .set_concentration(0.0)
         .set_concentration(0.1, "(cable 0 0.5 0.6)"_reg);
     result_t exp = {{0.000000, 0.000000, 0.000000},
@@ -178,7 +178,7 @@ TEST(diffusion, by_initial_concentration) {
 
 TEST(diffusion, by_event) {
     auto rec = linear{30, 3, 6}
-        .set_diffusivity(0.005)
+        .set_diffusivity(5e-10)
         .set_concentration(0.0)
         .add_inject()
         .add_event(0, 0.005);
@@ -235,7 +235,7 @@ TEST(diffusion, decay) {
 
 TEST(diffusion, decay_by_initial_concentration) {
     auto rec = linear{30, 3, 6}
-        .set_diffusivity(0.005)
+        .set_diffusivity(5e-10)
         .set_concentration(0.0)
         .set_concentration(0.1, "(cable 0 0.5 0.6)"_reg)
         .add_decay();
@@ -264,7 +264,7 @@ TEST(diffusion, decay_by_initial_concentration) {
 
 TEST(diffusion, decay_by_event) {
     auto rec = linear{30, 3, 6}
-        .set_diffusivity(0.005)
+        .set_diffusivity(5e-10)
         .set_concentration(0.0)
         .add_decay()
         .add_inject()