diff --git a/Makefile b/Makefile
index 0598adf83a..84386fac19 100755
--- a/Makefile
+++ b/Makefile
@@ -23,14 +23,10 @@ OR_TOOLS_MINOR = 1
 ifeq ($(OR_TOOLS_TOP),)
   OR_ROOT =
 else
-  ifeq "$(SHELL)" "cmd.exe"
+  ifeq ($(OS), Windows_NT)
     OR_ROOT = $(OR_TOOLS_TOP)\\
   else
-    ifeq "$(SHELL)" "sh.exe"
-      OR_ROOT = $(OR_TOOLS_TOP)\\
-    else
-      OR_ROOT = $(OR_TOOLS_TOP)/
-    endif
+    OR_ROOT = $(OR_TOOLS_TOP)/
   endif
 endif
 
diff --git a/makefiles/Makefile.port b/makefiles/Makefile.port
index c5e3508d9a..79e63b3127 100755
--- a/makefiles/Makefile.port
+++ b/makefiles/Makefile.port
@@ -3,14 +3,10 @@ SPACE := $(empty) $(empty)
 BACKSLASH_SPACE := $(empty)\ $(empty)
 
 # Let's discover something about where we run
-ifeq "$(SHELL)" "cmd.exe"
+ifeq ($(OS), Windows_NT)
   SYSTEM = win
 else
-  ifeq "$(SHELL)" "sh.exe"
-    SYSTEM = win
-  else
-    SYSTEM = unix
-  endif
+  SYSTEM = unix
 endif
 
 # Unix specific part.
@@ -213,3 +209,4 @@ ifeq ("$(SYSTEM)","unix")
 else
 	@echo CMAKE_PLATFORM = $(CMAKE_PLATFORM)
 endif
+