diff --git a/indra/newview/app_settings/shaders/class1/deferred/srgb.glsl b/indra/newview/app_settings/shaders/class1/deferred/srgb.glsl
index 177f6c25f8bd03236013c6b945fd895ea33caf0e..d532835bf10fb27437ce9a5a8d1e173da02844ad 100644
--- a/indra/newview/app_settings/shaders/class1/deferred/srgb.glsl
+++ b/indra/newview/app_settings/shaders/class1/deferred/srgb.glsl
@@ -23,6 +23,8 @@
  * $/LicenseInfo$
  */
 
+// OLD_SELECT work-around missing mix(vec3,vec,bvec3) in older GLSL versions (*cough* MAC *cough*)
+
 vec3 srgb_to_linear(vec3 cs)
 {
 	
@@ -32,7 +34,17 @@ vec3 srgb_to_linear(vec3 cs)
 
 	vec3 low_range = cs / vec3(12.92);
 	vec3 high_range = pow((cs+vec3(0.055))/vec3(1.055), vec3(2.4));
+
+	bvec3 lte = lessThanEqual(cs,vec3(0.04045));
+#ifdef OLD_SELECT
+	vec3 result;
+	result.r = lte.r ? low_range.r : high_range.r;
+	result.g = lte.g ? low_range.g : high_range.g;
+	result.b = lte.b ? low_range.b : high_range.b;
+    return result;
+#else
 	return mix(high_range, low_range, lessThanEqual(cs,vec3(0.04045)));
+#endif
 }
 
 vec3 linear_to_srgb(vec3 cl)
@@ -45,5 +57,17 @@ vec3 linear_to_srgb(vec3 cl)
 	cl = clamp(cl, vec3(0), vec3(1));
 	vec3 low_range  = cl * 12.92;
 	vec3 high_range = 1.055 * pow(cl, vec3(0.41666)) - 0.055;
+
+	bvec3 lt = lessThan(cl,vec3(0.0031308));
+
+#ifdef OLD_SELECT
+	vec3 result;
+	result.r = lt.r ? low_range.r : high_range.r;
+	result.g = lt.g ? low_range.g : high_range.g;
+	result.b = lt.b ? low_range.b : high_range.b;
+    return result;
+#else
 	return mix(high_range, low_range, lessThan(cl,vec3(0.0031308)));
+#endif
 }
+
diff --git a/indra/newview/llviewershadermgr.cpp b/indra/newview/llviewershadermgr.cpp
index f17e88f31200c3c2ee48cf1ff3d82400011bba47..6e2139ea9e35552e1bb7cc158172e7f22c0cb81b 100755
--- a/indra/newview/llviewershadermgr.cpp
+++ b/indra/newview/llviewershadermgr.cpp
@@ -911,7 +911,6 @@ BOOL LLViewerShaderMgr::loadBasicShaders()
 	index_channels.push_back(-1);	 shaders.push_back( make_pair( "windlight/atmosphericsF.glsl",			mVertexShaderLevel[SHADER_WINDLIGHT] ) );
 	index_channels.push_back(-1);	 shaders.push_back( make_pair( "windlight/transportF.glsl",				mVertexShaderLevel[SHADER_WINDLIGHT] ) );	
 	index_channels.push_back(-1);	 shaders.push_back( make_pair( "environment/waterFogF.glsl",				mVertexShaderLevel[SHADER_WATER] ) );
-	index_channels.push_back(-1);	 shaders.push_back( make_pair( "deferred/srgb.glsl",				mVertexShaderLevel[SHADER_DEFERRED] ) );
 	index_channels.push_back(-1);	 shaders.push_back( make_pair( "lighting/lightNonIndexedF.glsl",					mVertexShaderLevel[SHADER_LIGHTING] ) );
 	index_channels.push_back(-1);	 shaders.push_back( make_pair( "lighting/lightAlphaMaskNonIndexedF.glsl",					mVertexShaderLevel[SHADER_LIGHTING] ) );
 	index_channels.push_back(-1);	 shaders.push_back( make_pair( "lighting/lightFullbrightNonIndexedF.glsl",			mVertexShaderLevel[SHADER_LIGHTING] ) );
@@ -937,6 +936,14 @@ BOOL LLViewerShaderMgr::loadBasicShaders()
 	index_channels.push_back(ch);	 shaders.push_back( make_pair( "lighting/lightShinyWaterF.glsl",			mVertexShaderLevel[SHADER_LIGHTING] ) );
 	index_channels.push_back(ch);	 shaders.push_back( make_pair( "lighting/lightFullbrightShinyWaterF.glsl", mVertexShaderLevel[SHADER_LIGHTING] ) );
 
+	index_channels.push_back(-1);	 shaders.push_back( make_pair( "deferred/srgb.glsl",				mVertexShaderLevel[SHADER_DEFERRED] ) );
+
+// work-around for missing mix(vec3,vec3,bvec3) on decrepit GLSLs
+//
+#if LL_DARWIN
+    attribs["OLD_SELECT"] = "1";
+#endif
+
 	for (U32 i = 0; i < shaders.size(); i++)
 	{
 		// Note usage of GL_FRAGMENT_SHADER_ARB