diff --git a/SCons/Config/default b/SCons/Config/default
index 9cd7b3eb..f010cbe0 100644
--- a/SCons/Config/default
+++ b/SCons/Config/default
@@ -17,7 +17,7 @@ defenv['STDCALL'] = ''
 
 ### defines
 
-defenv.Append(CPPDEFINES = {'NSISCALL' : '$STDCALL'})
+defenv.Append(CPPDEFINES = [('NSISCALL', '$STDCALL')])
 
 ### stub environment
 
diff --git a/SCons/Config/gnu b/SCons/Config/gnu
index 2b276be9..f6ed7a1c 100644
--- a/SCons/Config/gnu
+++ b/SCons/Config/gnu
@@ -35,7 +35,7 @@ defenv['STDCALL'] = '__attribute__((__stdcall__))'
 
 ### defines
 
-defenv.Append(CPPDEFINES = {'NSISCALL' : ' $STDCALL'})
+defenv.Append(CPPDEFINES = [('NSISCALL', '$STDCALL')])
 
 ### helper functions
 
diff --git a/SCons/Config/hpc++ b/SCons/Config/hpc++
index 361e0a06..558f0e7b 100644
--- a/SCons/Config/hpc++
+++ b/SCons/Config/hpc++
@@ -17,7 +17,7 @@ defenv['STDCALL'] = ''
 
 ### defines
 
-defenv.Append(CPPDEFINES = {'NSISCALL' : '$STDCALL'})
+defenv.Append(CPPDEFINES = [('NSISCALL', '$STDCALL')])
 
 ### stub environment
 
diff --git a/SCons/Config/ms b/SCons/Config/ms
index 1e2a7654..064222c0 100644
--- a/SCons/Config/ms
+++ b/SCons/Config/ms
@@ -23,7 +23,7 @@ else:
 
 ### defines
 
-defenv.Append(CPPDEFINES = {'NSISCALL' : '$STDCALL'})
+defenv.Append(CPPDEFINES = [('NSISCALL', '$STDCALL')])
 
 ### asm