diff --git a/release/scripts/ui/properties_particle.py b/release/scripts/ui/properties_particle.py
index 276643b32ff..9315b209861 100644
--- a/release/scripts/ui/properties_particle.py
+++ b/release/scripts/ui/properties_particle.py
@@ -221,7 +221,7 @@ class PARTICLE_PT_hair_dynamics(ParticleButtonsPanel):
         sub.itemR(cloth, "pin_stiffness", text="Stiffness")
         sub.itemR(cloth, "mass")
         sub.itemR(cloth, "bending_stiffness", text="Bending")
-        sub.itemR(cloth, "internal_friction", slider="True")
+        sub.itemR(cloth, "internal_friction", slider=True)
 
         col = split.column()
 
@@ -410,9 +410,9 @@ class PARTICLE_PT_physics(ParticleButtonsPanel):
             col = sub.column(align=True)
             col.active = boids.allow_flight
             col.itemR(boids, "air_max_speed")
-            col.itemR(boids, "air_min_speed", slider="True")
-            col.itemR(boids, "air_max_acc", slider="True")
-            col.itemR(boids, "air_max_ave", slider="True")
+            col.itemR(boids, "air_min_speed", slider=True)
+            col.itemR(boids, "air_max_acc", slider=True)
+            col.itemR(boids, "air_max_ave", slider=True)
             col.itemR(boids, "air_personal_space")
             row = col.row()
             row.active = (boids.allow_land or boids.allow_climb) and boids.allow_flight
@@ -423,8 +423,8 @@ class PARTICLE_PT_physics(ParticleButtonsPanel):
             col.active = boids.allow_land or boids.allow_climb
             col.itemR(boids, "land_max_speed")
             col.itemR(boids, "land_jump_speed")
-            col.itemR(boids, "land_max_acc", slider="True")
-            col.itemR(boids, "land_max_ave", slider="True")
+            col.itemR(boids, "land_max_acc", slider=True)
+            col.itemR(boids, "land_max_ave", slider=True)
             col.itemR(boids, "land_personal_space")
             col.itemR(boids, "land_stick_force")
 
diff --git a/source/blender/python/intern/bpy_rna.c b/source/blender/python/intern/bpy_rna.c
index d25a240990b..cdf4f518b51 100644
--- a/source/blender/python/intern/bpy_rna.c
+++ b/source/blender/python/intern/bpy_rna.c
@@ -591,9 +591,16 @@ int pyrna_py_to_prop(PointerRNA *ptr, PropertyRNA *prop, void *data, PyObject *v
 		switch (type) {
 		case PROP_BOOLEAN:
 		{
-			int param = PyObject_IsTrue( value );
+			int param;
+			/* prefer not to have an exception here
+			 * however so many poll functions return None or a valid Object.
+			 * its a hassle to convert these into a bool before returning, */
+			if(RNA_property_flag(prop) & PROP_RETURN)
+				param = PyObject_IsTrue( value );
+			else
+				param = PyLong_AsSsize_t( value );
 			
-			if( param < 0 ) {
+			if( param < 0 || param > 1) {
 				PyErr_Format(PyExc_TypeError, "%.200s expected True/False or 0/1", error_prefix);
 				return -1;
 			} else {
@@ -681,7 +688,7 @@ int pyrna_py_to_prop(PointerRNA *ptr, PropertyRNA *prop, void *data, PyObject *v
 				PyErr_Format(PyExc_TypeError, "%.200s expected a %.200s type", error_prefix, RNA_struct_identifier(ptype));
 				return -1;
 			} else if((flag & PROP_NEVER_NULL) && value == Py_None) {
-				PyErr_Format(PyExc_TypeError, "property can't be assigned a None value");
+				PyErr_Format(PyExc_TypeError, "%.200s does not suppory a 'None' assignment %.200s type", error_prefix, RNA_struct_identifier(ptype));
 				return -1;
 			} else {
 				BPy_StructRNA *param= (BPy_StructRNA*)value;
@@ -813,9 +820,9 @@ static int pyrna_py_to_prop_index(BPy_PropertyRNA *self, int index, PyObject *va
 		switch (type) {
 		case PROP_BOOLEAN:
 			{
-				int param = PyObject_IsTrue( value );
+				int param = PyLong_AsSsize_t( value );
 		
-				if( param < 0 ) {
+				if( param < 0 || param > 1) {
 					PyErr_SetString(PyExc_TypeError, "expected True/False or 0/1");
 					ret = -1;
 				} else {