diff --git a/PlayRho/Common/Fixed.hpp b/PlayRho/Common/Fixed.hpp
index 66b853807b..0c6190beba 100644
--- a/PlayRho/Common/Fixed.hpp
+++ b/PlayRho/Common/Fixed.hpp
@@ -761,6 +761,13 @@ namespace playrho
     {
         return Abs(x - y) <= Fixed<BT, FB>{0, static_cast<std::uint32_t>(ulp)};
     }
+    
+    /// @brief Gets an invalid value.
+    template <typename BT, unsigned int FB>
+    constexpr Fixed<BT, FB> GetInvalid() noexcept
+    {
+        return Fixed<BT, FB>::GetNaN();
+    }
 
     /// @brief Output stream operator.
     template <typename BT, unsigned int FB>
@@ -853,13 +860,6 @@ namespace playrho
         const auto result = lhs.Compare(rhs);
         return result == Fixed32::CmpResult::GreaterThan;
     }
-
-    /// @brief Gets an invalid value.
-    template <>
-    constexpr Fixed32 GetInvalid() noexcept
-    {
-        return Fixed32::GetNaN();
-    }
     
     /// @brief Gets the specialized name for the Fixed32 type.
     /// @details Provides an interface to a specialized function for getting C-style
@@ -951,13 +951,6 @@ namespace playrho
     template<> struct Wider<Fixed32> {
         using type = Fixed64; ///< Wider type.
     };
-
-    /// @brief Gets an invalid value.
-    template <>
-    constexpr Fixed64 GetInvalid() noexcept
-    {
-        return Fixed64::GetNaN();
-    }
     
     /// @brief Gets the specialized name for the Fixed64 type.
     /// @details Provides an interface to a specialized function for getting C-style
diff --git a/PlayRho/Common/Math.hpp b/PlayRho/Common/Math.hpp
index 0d2563aa46..ec46f31bf5 100644
--- a/PlayRho/Common/Math.hpp
+++ b/PlayRho/Common/Math.hpp
@@ -303,7 +303,8 @@ AlmostEqual(T x, T y, int ulp = 2)
 /// @note Modulo via std::fmod appears slower than via std::trunc.
 /// @sa ModuloViaTrunc
 template <typename T>
-inline auto ModuloViaFmod(T dividend, T divisor) noexcept
+inline typename std::enable_if<std::is_floating_point<T>::value, T>::type
+ModuloViaFmod(T dividend, T divisor) noexcept
 {
     // Note: modulo via std::fmod appears slower than via std::trunc.
     return static_cast<T>(std::fmod(dividend, divisor));
diff --git a/PlayRho/Dynamics/StepConf.hpp b/PlayRho/Dynamics/StepConf.hpp
index a843fb796f..b34fbb60b9 100644
--- a/PlayRho/Dynamics/StepConf.hpp
+++ b/PlayRho/Dynamics/StepConf.hpp
@@ -152,11 +152,9 @@ class StepConf
 
     /// @brief Target depth.
     /// @details Target depth of overlap for calculating the TOI for CCD elligible bodies.
-    /// @note Must be greater than 0.
-    /// @note Must not be subnormal.
-    /// @note Must be less than twice the world's minimum vertex radius.
+    /// @note Recommend value that's less than twice the world's minimum vertex radius.
     /// @note Used in the TOI phase of step processing.
-    Positive<Length> targetDepth = DefaultLinearSlop * Real{3};
+    Length targetDepth = DefaultLinearSlop * Real{3};
     
     /// @brief Tolerance.
     /// @details The acceptable plus or minus tolerance from the target depth for TOI calculations.
diff --git a/PlayRho/Dynamics/World.cpp b/PlayRho/Dynamics/World.cpp
index a298e332ce..0967e58719 100644
--- a/PlayRho/Dynamics/World.cpp
+++ b/PlayRho/Dynamics/World.cpp
@@ -1387,6 +1387,9 @@ World::UpdateContactsData World::UpdateContactTOIs(const StepConf& conf)
         // Compute the TOI for this contact (one or both bodies are active and impenetrable).
         // Computes the time of impact in interval [0, 1]
         const auto output = CalcToi(c, toiConf);
+        assert((output.state == TOIOutput::State::e_touching)
+            || (output.state == TOIOutput::State::e_separated)
+            || (output.state == TOIOutput::State::e_overlapped));
         
         // Use Min function to handle floating point imprecision which possibly otherwise
         // could provide a TOI that's greater than 1.
diff --git a/Testbed/Tests/SolarSystem.hpp b/Testbed/Tests/SolarSystem.hpp
index fb391d422a..6449b785b7 100644
--- a/Testbed/Tests/SolarSystem.hpp
+++ b/Testbed/Tests/SolarSystem.hpp
@@ -83,6 +83,12 @@ class SolarSystem: public Test
         os << " km (" << minName << "), to ";
         os << static_cast<float>(Real{maxRadius / 1_km});
         os << " km (" << maxName << ").";
+        if (std::is_same<Real, float>::value)
+        {
+            os << "\n\n";
+            os << "Note: recompile with playrho::Real set to use double (or bigger)";
+            os << " for collisions to work better at these scales.";
+        }
 
         auto conf = Test::Conf{};
         conf.description = os.str();
@@ -93,7 +99,7 @@ class SolarSystem: public Test
         conf.neededSettings |= (1u << NeedDrawLabelsField);
         conf.neededSettings |= (1u << NeedMaxTranslation);
         conf.neededSettings |= (1u << NeedDeltaTime);
-        conf.settings.linearSlop = 1000.0f; // minRadius / 1000_m;
+        conf.settings.linearSlop = 200 * 1000.0f; // 200_km;
         conf.settings.cameraZoom = 2.2e11f;
         conf.settings.drawLabels = true;
         conf.settings.maxTranslation = std::numeric_limits<float>::infinity();
@@ -106,7 +112,7 @@ class SolarSystem: public Test
     SolarSystem(): Test(GetTestConf())
     {
         m_world.SetGravity(LinearAcceleration2{});
-        const auto DynamicBD = BodyDef{}.UseType(BodyType::Dynamic);
+        const auto DynamicBD = BodyDef{}.UseType(BodyType::Dynamic).UseBullet(true);
         for (auto& sso: SolarSystemBodies)
         {
             const auto p = sso.orbitalPeriod;