diff --git a/Changes b/Changes
index d2b04a9a76..18564d6106 100644
--- a/Changes
+++ b/Changes
@@ -15,9 +15,11 @@ Build
   - Added `PYBIND11_INCLUDE_PATH` option.
   - Added `VDB_PYTHON_PATH` to USD tests.
   - Added `INSTALL_CREATE_SYMLINKS`, which allows you to disable the creation of version symlinks at the end of the install.
+  - Added `USG_SHIMLIB_PATH` which may be necessary to run nuke tests.
 
 - CI :
   - IECoreHoudini tests updated to pass on newer environments.
+  - IECoreGL tests updated with relaxed precisions for image comparisons.
 
 10.5.10.0 (relative to 10.5.9.5)
 =========
diff --git a/SConstruct b/SConstruct
index e2b5ac9a14..d359269e9a 100644
--- a/SConstruct
+++ b/SConstruct
@@ -353,6 +353,13 @@ o.Add(
 	"",
 )
 
+o.Add(
+	"USG_SHIMLIB_PATH",
+	"The path to the FnUsdShim to use for Nuke. This may be necessary to run the tests.",
+	"",
+)
+
+
 # OpenGL options
 
 try :
@@ -2589,6 +2596,7 @@ nukeTestEnv["ENV"]["NUKE_PATH"] = "plugins/nuke"
 nukeTestEnv["ENV"]["IECORE_OP_PATHS"] = "test/IECoreNuke/ops:test/IECore/ops"
 # prepend OIIO LIB PATH to library path to support custom OIIO with specific dependencies
 nukeTestEnv["ENV"][libraryPathEnvVar] = "{}:{}".format( nukeTestEnv.subst( "$OIIO_LIB_PATH" ), nukeTestEnv["ENV"][libraryPathEnvVar] )
+nukeTestEnv["ENV"]["USG_SHIMLIB_PATH"] = nukeTestEnv["USG_SHIMLIB_PATH"]
 
 if doConfigure :
 
diff --git a/config/ie/options b/config/ie/options
index f4868268ff..f345f6d331 100644
--- a/config/ie/options
+++ b/config/ie/options
@@ -366,31 +366,18 @@ VDB_INCLUDE_PATH = os.path.join(
 VDB_LIB_PATH = os.path.join(
     "/software", "apps", "OpenVDB", vdbVersion, platform, compiler, compilerVersion, "lib"
 )
-if LooseVersion(vdbVersion) < LooseVersion("10") and targetApp:
-    VDB_PYTHON_PATH = os.path.join(
-        "/software",
-        "apps",
-        "OpenVDB",
-        vdbVersion,
-        platform,
-        compiler,
-        compilerVersion,
-        "python",
-        "lib",
-        "python" + pythonVersion,
-    )
-
-else:
-    VDB_PYTHON_PATH = os.path.join(
-        "/software",
-        "apps",
-        "OpenVDB",
-        vdbVersion,
-        platform,
-        compiler,
-        compilerVersion,
-        "python",
-    )
+VDB_PYTHON_PATH = os.path.join(
+    "/software",
+    "apps",
+    "OpenVDB",
+    vdbVersion,
+    platform,
+    compiler,
+    compilerVersion,
+    "python",
+    "lib",
+    "python" + pythonVersion,
+)
 
 
 PYBIND11_INCLUDE_PATH = os.path.join(
@@ -513,6 +500,15 @@ if targetApp == "nuke":
     nukeReg = IEEnv.registry["apps"]["nuke"][nukeVersion][platform]
     NUKE_ROOT = nukeReg["location"]
     NUKE_LICENSE_FILE = nukeReg["wrapperEnvVars"]["foundry_LICENSE"]
+    USG_SHIMLIB_PATH = os.path.join(
+        "/software",
+        "apps",
+        "FnUsdShim",
+        nukeReg["compatibilityVersion"],
+        platform,
+        compiler,
+        compilerVersion,
+    )
     INSTALL_NUKELIB_NAME = os.path.join(appPrefix, "lib", "$IECORE_NAME{}".format(ieCoreLibSuffix))
     INSTALL_NUKEPYTHON_DIR = os.path.join(appPrefix, "python")
     INSTALL_NUKEICON_DIR = os.path.join(appPrefix, "icons")
diff --git a/test/IECoreGL/Camera.py b/test/IECoreGL/Camera.py
index 9840160f62..8476a25b25 100644
--- a/test/IECoreGL/Camera.py
+++ b/test/IECoreGL/Camera.py
@@ -64,7 +64,7 @@ def testPositioning( self ) :
 		i = IECore.Reader.create( os.path.join( os.path.dirname( __file__ ), "output", "testCamera.tif" ) ).read()
 		dimensions = i.dataWindow.size() + imath.V2i( 1 )
 		midpoint = dimensions.x * dimensions.y//2 + dimensions.x//2
-		self.assertEqual( i["G"][midpoint], 0 )
+		self.assertAlmostEqual( i["G"][midpoint], 0, 6 )
 
 		# render a plane at z = 0 with the camera moved back a touch to see it
 		r = IECoreGL.Renderer()
@@ -87,7 +87,7 @@ def testPositioning( self ) :
 		i = IECore.Reader.create( os.path.join( os.path.dirname( __file__ ), "output", "testCamera.tif" ) ).read()
 		dimensions = i.dataWindow.size() + imath.V2i( 1 )
 		midpoint = dimensions.x * dimensions.y//2 + dimensions.x//2
-		self.assertEqual( i["A"][midpoint], 1 )
+		self.assertAlmostEqual( i["A"][midpoint], 1, 6 )
 
 	def testXYOrientation( self ) :
 
@@ -113,15 +113,15 @@ def testXYOrientation( self ) :
 		i = IECore.Reader.create( os.path.join( os.path.dirname( __file__ ), "output", "testCamera.tif" ) ).read()
 		dimensions = i.dataWindow.size() + imath.V2i( 1 )
 		index = dimensions.x * dimensions.y//2 + dimensions.x - 1
-		self.assertEqual( i["A"][index], 1 )
+		self.assertAlmostEqual( i["A"][index], 1, 6 )
 		self.assertAlmostEqual( i["R"][index], 1, 6 )
-		self.assertEqual( i["G"][index], 0 )
-		self.assertEqual( i["B"][index], 0 )
+		self.assertAlmostEqual( i["G"][index], 0, 6 )
+		self.assertAlmostEqual( i["B"][index], 0, 6 )
 		index = dimensions.x//2
-		self.assertEqual( i["A"][index], 1 )
-		self.assertEqual( i["R"][index], 0 )
+		self.assertAlmostEqual( i["A"][index], 1, 6 )
+		self.assertAlmostEqual( i["R"][index], 0, 6 )
 		self.assertAlmostEqual( i["G"][index], 1, 6 )
-		self.assertEqual( i["B"][index], 0 )
+		self.assertAlmostEqual( i["B"][index], 0, 6 )
 
 	def setUp( self ) :
 
diff --git a/test/IECoreGL/ImmediateRenderer.py b/test/IECoreGL/ImmediateRenderer.py
index d381690d28..d97acac24b 100644
--- a/test/IECoreGL/ImmediateRenderer.py
+++ b/test/IECoreGL/ImmediateRenderer.py
@@ -76,20 +76,20 @@ def test( self ) :
 		i = IECore.Reader.create( outputFileName ).read()
 		dimensions = i.dataWindow.size() + imath.V2i( 1 )
 		index = int(dimensions.x * 0.5)
-		self.assertEqual( i["A"][index], 1 )
+		self.assertAlmostEqual( i["A"][index], 1, 6 )
 		self.assertAlmostEqual( i["R"][index], 1, 6 )
 		self.assertAlmostEqual( i["G"][index], 1, 6 )
-		self.assertEqual( i["B"][index], 0 )
+		self.assertAlmostEqual( i["B"][index], 0, 6 )
 		index = dimensions.x * int(dimensions.y * 0.5) + int(dimensions.x * 0.5)
-		self.assertEqual( i["A"][index], 1 )
-		self.assertEqual( i["R"][index], 0 )
-		self.assertEqual( i["G"][index], 0 )
+		self.assertAlmostEqual( i["A"][index], 1, 6 )
+		self.assertAlmostEqual( i["R"][index], 0, 6 )
+		self.assertAlmostEqual( i["G"][index], 0, 6 )
 		self.assertAlmostEqual( i["B"][index], 1, 6 )
 		index = 0
-		self.assertEqual( i["A"][index], 0 )
-		self.assertEqual( i["R"][index], 0 )
-		self.assertEqual( i["G"][index], 0 )
-		self.assertEqual( i["B"][index], 0 )
+		self.assertAlmostEqual( i["A"][index], 0, 6 )
+		self.assertAlmostEqual( i["R"][index], 0, 6 )
+		self.assertAlmostEqual( i["G"][index], 0, 6 )
+		self.assertAlmostEqual( i["B"][index], 0, 6 )
 
 	def setUp( self ) :
 
diff --git a/test/IECoreGL/MeshPrimitiveTest.py b/test/IECoreGL/MeshPrimitiveTest.py
index 7fdd3f6eea..4e4aad7546 100644
--- a/test/IECoreGL/MeshPrimitiveTest.py
+++ b/test/IECoreGL/MeshPrimitiveTest.py
@@ -158,13 +158,13 @@ def testUniformCs( self ) :
 		dimensions = image.dataWindow.size() + imath.V2i( 1 )
 		index = dimensions.x * int(dimensions.y * 0.75) + int(dimensions.x * 0.25)
 		self.assertAlmostEqual( image["R"][index], 1, 6 )
-		self.assertEqual( image["G"][index], 0 )
-		self.assertEqual( image["B"][index], 0 )
+		self.assertAlmostEqual( image["G"][index], 0, 6 )
+		self.assertAlmostEqual( image["B"][index], 0, 6 )
 
 		index = dimensions.x * int(dimensions.y * 0.75) + int(dimensions.x * 0.75)
-		self.assertEqual( image["R"][index], 0 )
+		self.assertAlmostEqual( image["R"][index], 0, 6 )
 		self.assertAlmostEqual( image["G"][index], 1, 6 )
-		self.assertEqual( image["B"][index], 0 )
+		self.assertAlmostEqual( image["B"][index], 0, 6 )
 
 		index = dimensions.x * int(dimensions.y * 0.25) + int(dimensions.x * 0.75)
 		self.assertAlmostEqual( image["R"][index], 1, 6 )
@@ -172,8 +172,8 @@ def testUniformCs( self ) :
 		self.assertAlmostEqual( image["B"][index], 1, 6 )
 
 		index = dimensions.x * int(dimensions.y * 0.25) + int(dimensions.x * 0.25)
-		self.assertEqual( image["R"][index], 0 )
-		self.assertEqual( image["G"][index], 0 )
+		self.assertAlmostEqual( image["R"][index], 0, 6 )
+		self.assertAlmostEqual( image["G"][index], 0, 6 )
 		self.assertAlmostEqual( image["B"][index], 1, 6 )
 
 	def testBound( self ) :
@@ -192,10 +192,10 @@ def testFaceNormals( self ) :
 		#include "IECoreGL/FragmentShader.h"
 		IECOREGL_FRAGMENTSHADER_IN vec3 fragmentN;
 
- 		void main()
- 		{
- 			gl_FragColor = vec4( fragmentN, 1.0 );
- 		}
+		void main()
+		{
+			gl_FragColor = vec4( fragmentN, 1.0 );
+		}
 		"""
 
 		r = IECoreGL.Renderer()
@@ -224,8 +224,8 @@ def testFaceNormals( self ) :
 		image = IECore.Reader.create( self.outputFileName ).read()
 		dimensions = image.dataWindow.size() + imath.V2i( 1 )
 		index = dimensions.x * dimensions.y//2 + dimensions.x//2
-		self.assertEqual( image["R"][index], 0 )
-		self.assertEqual( image["G"][index], 0 )
+		self.assertAlmostEqual( image["R"][index], 0, 6 )
+		self.assertAlmostEqual( image["G"][index], 0, 6 )
 		self.assertAlmostEqual( image["B"][index], 1, 6 )
 
 	def testIndexedUV( self ) :
diff --git a/test/IECoreGL/Renderer.py b/test/IECoreGL/Renderer.py
index e977c2f879..effdd751ca 100644
--- a/test/IECoreGL/Renderer.py
+++ b/test/IECoreGL/Renderer.py
@@ -282,17 +282,17 @@ def testStackBug( self ) :
 		index = dimensions.x * int(dimensions.y * 0.5) + int(dimensions.x * 0.5)
 		self.assertAlmostEqual( i["R"][index], 1, 6 )
 		self.assertAlmostEqual( i["G"][index], 1, 6 )
-		self.assertEqual( i["B"][index], 0 )
+		self.assertAlmostEqual( i["B"][index], 0, 6 )
 
 		index = dimensions.x * int(dimensions.y * 0.5)
 		self.assertAlmostEqual( i["R"][index], 1, 6 )
-		self.assertEqual( i["G"][index], 0 )
-		self.assertEqual( i["B"][index], 0 )
+		self.assertAlmostEqual( i["G"][index], 0, 6 )
+		self.assertAlmostEqual( i["B"][index], 0, 6 )
 
 		index = dimensions.x * int(dimensions.y * 0.5) + int(dimensions.x * 1) - 1
 		self.assertAlmostEqual( i["R"][index], 1, 6 )
-		self.assertEqual( i["G"][index], 0 )
-		self.assertEqual( i["B"][index], 0 )
+		self.assertAlmostEqual( i["G"][index], 0, 6 )
+		self.assertAlmostEqual( i["B"][index], 0, 6 )
 
 	def testPrimVars( self ) :
 
@@ -345,18 +345,18 @@ def testPrimVars( self ) :
 		i = IECore.Reader.create( os.path.join( os.path.dirname( __file__ ), "output", "testPrimVars.tif" ) ).read()
 		dimensions = i.dataWindow.size() + imath.V2i( 1 )
 		index = dimensions.x * int(dimensions.y * 0.5)
-		self.assertEqual( i["R"][index], 0 )
+		self.assertAlmostEqual( i["R"][index], 0, 6 )
 		self.assertAlmostEqual( i["G"][index], 1, 6 )
-		self.assertEqual( i["B"][index], 0 )
+		self.assertAlmostEqual( i["B"][index], 0, 6 )
 
 		index = dimensions.x * int(dimensions.y * 0.5) + int(dimensions.x * 0.5)
 		self.assertAlmostEqual( i["R"][index], 1, 6 )
-		self.assertEqual( i["G"][index], 0 )
-		self.assertEqual( i["B"][index], 0 )
+		self.assertAlmostEqual( i["G"][index], 0, 6 )
+		self.assertAlmostEqual( i["B"][index], 0, 6 )
 
 		index = dimensions.x * int(dimensions.y * 0.5) + int(dimensions.x * 1) - 1
-		self.assertEqual( i["R"][index], 0 )
-		self.assertEqual( i["G"][index], 0 )
+		self.assertAlmostEqual( i["R"][index], 0, 6 )
+		self.assertAlmostEqual( i["G"][index], 0, 6 )
 		self.assertAlmostEqual( i["B"][index], 1, 6 )
 
 	## \todo Make this assert something
diff --git a/test/IECoreGL/ShadingTest.py b/test/IECoreGL/ShadingTest.py
index 0720e2fb1a..9cffe9f290 100644
--- a/test/IECoreGL/ShadingTest.py
+++ b/test/IECoreGL/ShadingTest.py
@@ -825,10 +825,11 @@ def testVertexCsDoesntAffectWireframe( self ) :
 		# wireframe is green, and vertex Cs is black,
 		# so there should be no contribution from
 		# wireframe or solid shading in the red channel.
-		self.assertEqual( sum( image["R"] ), 0 )
+		self.assertAlmostEqual( sum( image["R"] ), 0, 4 )
 		# black vertex colour should have no effect on
 		# green wireframe, so we should have some wireframe
 		# contribution in the green channel.
+		self.assertNotAlmostEqual( sum( image["G"] ), 0, 4 )
 		self.assertTrue( sum( image["G"] ) > 0 )
 
 	def testUniformFloatArrayParameters( self ) :