diff --git a/src/tools/clang.lua b/src/tools/clang.lua
index fd4bc5c7..af0cd7d8 100644
--- a/src/tools/clang.lua
+++ b/src/tools/clang.lua
@@ -214,8 +214,10 @@
 
 		if tool == "ar" then
 			return "ar"
-		else
+		elseif tool == "cc" then
 			return "clang"
+		elseif tool == "cxx" then
+			return "clang++"
 		end
 
 	end
diff --git a/src/tools/gcc.lua b/src/tools/gcc.lua
index ac905106..77f5c5ee 100644
--- a/src/tools/gcc.lua
+++ b/src/tools/gcc.lua
@@ -96,6 +96,7 @@
 			Strict = "-ffloat-store",
 		},
 		optimize = {
+			Off = "-O0",
 			On = "-O2",
 			Size = "-Os",
 			Speed = "-O3",
diff --git a/tests/actions/make/cpp/test_clang.lua b/tests/actions/make/cpp/test_clang.lua
index 68ff89e3..89425ff6 100644
--- a/tests/actions/make/cpp/test_clang.lua
+++ b/tests/actions/make/cpp/test_clang.lua
@@ -32,7 +32,7 @@
 		test.capture [[
 ifeq ($(config),debug)
   CC = clang
-  CXX = clang
+  CXX = clang++
   AR = ar
   		]]
 	end
diff --git a/tests/tools/test_gcc.lua b/tests/tools/test_gcc.lua
index c708d7cb..4514c5a4 100644
--- a/tests/tools/test_gcc.lua
+++ b/tests/tools/test_gcc.lua
@@ -114,6 +114,11 @@
 		test.isequal({ "-msse2" }, gcc.getcflags(cfg))
 	end
 
+	function suite.cflags_onNoOptimize()
+		optimize "Off"
+		prepare()
+		test.isequal({ "-O0" }, gcc.getcflags(cfg))
+	end
 
 --
 -- Check the translation of CXXFLAGS.