diff --git a/make_helpers/cygwin.mk b/make_helpers/cygwin.mk
index f99be13..e69c0b1 100644
--- a/make_helpers/cygwin.mk
+++ b/make_helpers/cygwin.mk
@@ -37,4 +37,7 @@
 
     include ${MAKE_HELPERS_DIRECTORY}unix.mk
 
+    # In cygwin executable files have the Windows .exe extension type.
+    BIN_EXT := .exe
+
 endif
diff --git a/make_helpers/msys.mk b/make_helpers/msys.mk
index ca0f72b..188dc6c 100644
--- a/make_helpers/msys.mk
+++ b/make_helpers/msys.mk
@@ -37,5 +37,8 @@
 
     include ${MAKE_HELPERS_DIRECTORY}unix.mk
 
+    # In MSYS executable files have the Windows .exe extension type.
+    BIN_EXT := .exe
+
 endif
 
diff --git a/make_helpers/windows.mk b/make_helpers/windows.mk
index 92cc8f6..394df3a 100644
--- a/make_helpers/windows.mk
+++ b/make_helpers/windows.mk
@@ -38,9 +38,9 @@
     WINDOWS_MK := $(lastword $(MAKEFILE_LIST))
 
     ECHO_BLANK_LINE := @cmd /c echo.
-
     DIR_DELIM := $(strip \)
-    PATH_SEP := ;
+    BIN_EXT   := .exe
+    PATH_SEP  := ;
 
     # For some Windows native commands there is a problem with the directory delimiter.
     # Make uses / (slash) and the commands expect \ (backslash)