3 files changed, 7 insertions, 4 deletions
diff --git a/build/rapier_testbed2d/Cargo.toml b/build/rapier_testbed2d/Cargo.toml
index 4c3872f..d31cdff 100644
--- a/build/rapier_testbed2d/Cargo.toml
+++ b/build/rapier_testbed2d/Cargo.toml
@@ -26,7 +26,7 @@ other-backends = [ "wrapped2d", "nphysics2d" ]
 
 
 [dependencies]
-nalgebra   = "0.25"
+nalgebra   = { version = "0.25", features = [ "rand" ] }
 kiss3d     = { version = "0.30", features = [ "conrod" ] }
 rand       = "0.8"
 rand_pcg   = "0.3"
diff --git a/build/rapier_testbed3d/Cargo.toml b/build/rapier_testbed3d/Cargo.toml
index d14a1de..2a599a4 100644
--- a/build/rapier_testbed3d/Cargo.toml
+++ b/build/rapier_testbed3d/Cargo.toml
@@ -25,7 +25,7 @@ parallel = [ "rapier3d/parallel", "num_cpus" ]
 other-backends = [ "physx", "physx-sys", "glam", "nphysics3d" ]
 
 [dependencies]
-nalgebra   = "0.25"
+nalgebra   = { version = "0.25", features = [ "rand" ] }
 kiss3d     = { version = "0.30", features = [ "conrod" ] }
 rand       = "0.8"
 rand_pcg   = "0.3"
diff --git a/src/dynamics/rigid_body.rs b/src/dynamics/rigid_body.rs
index 32c0cca..88f4069 100644
--- a/src/dynamics/rigid_body.rs
+++ b/src/dynamics/rigid_body.rs
@@ -6,6 +6,7 @@ use crate::math::{
     AngVector, AngularInertia, Isometry, Point, Real, Rotation, Translation, Vector,
 };
 use crate::utils::{self, WCross, WDot};
+use na::ComplexField;
 use num::Zero;
 
 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
@@ -804,7 +805,8 @@ impl RigidBodyBuilder {
     /// Sets the angular inertia of this rigid-body.
     #[cfg(feature = "dim2")]
     pub fn principal_angular_inertia(mut self, inertia: Real) -> Self {
-        self.mass_properties.inv_principal_inertia_sqrt = utils::inv(inertia);
+        self.mass_properties.inv_principal_inertia_sqrt =
+            utils::inv(ComplexField::sqrt(inertia.max(0.0)));
         self
     }
 
@@ -829,7 +831,8 @@ impl RigidBodyBuilder {
     /// attached to this rigid-body.
     #[cfg(feature = "dim3")]
     pub fn principal_angular_inertia(mut self, inertia: AngVector<Real>) -> Self {
-        self.mass_properties.inv_principal_inertia_sqrt = inertia.map(utils::inv);
+        self.mass_properties.inv_principal_inertia_sqrt =
+            inertia.map(|e| utils::inv(ComplexField::sqrt(e.max(0.0))));
         self
     }