Index: build/premake/extern_libs5.lua
===================================================================
--- build/premake/extern_libs5.lua
+++ build/premake/extern_libs5.lua
@@ -37,6 +37,18 @@
 	sysincludedirs { third_party_source_dir .. extern_lib .. "/include" }
 end
 
+local function get_wx_config_path()
+	local wx_config_path = os.getenv("WX_CONFIG")
+        if not wx_config_path then
+		local haswxconfig = os.outputof("which wx-config")
+		if not haswxconfig then
+			error("WX_CONFIG must be set or wx-config must be present when --atlas is passed.")
+		end
+		wx_config_path="wx-config"
+	end
+	return wx_config_path
+end
+
 pkgconfig = require "pkgconfig"
 
 -- Configure pkgconfig for MacOSX systems
@@ -690,16 +702,14 @@
 			else
 				-- wxwidgets does not come with a definition file for pkg-config,
 				-- so we have to use wxwidgets' own config tool
-				wx_config_path = os.getenv("WX_CONFIG") or "wx-config"
-				pkgconfig.add_includes(nil, wx_config_path, "--unicode=yes --cxxflags")
+				pkgconfig.add_includes(nil, get_wx_config_path(), "--unicode=yes --cxxflags")
 			end
 		end,
 		link_settings = function()
 			if os.istarget("windows") then
 				libdirs { libraries_dir.."wxwidgets/lib/vc_lib" }
 			else
-				wx_config_path = os.getenv("WX_CONFIG") or "wx-config"
-				pkgconfig.add_links(nil, wx_config_path, "--unicode=yes --libs std,gl")
+				pkgconfig.add_links(nil, get_wx_config_path(), "--unicode=yes --libs std,gl")
 			end
 		end,
 	},