diff --git a/Source/Additions/GSObjCRuntime.m b/Source/Additions/GSObjCRuntime.m
index fc3f63c7d..6c716541e 100644
--- a/Source/Additions/GSObjCRuntime.m
+++ b/Source/Additions/GSObjCRuntime.m
@@ -1090,8 +1090,7 @@ GSObjCGetVal(NSObject *self, const char *key, SEL sel,
 	    }
 	    break;
 
-#if __GNUC__ != 2
-#ifdef  _C_BOOL
+#if __GNUC__ != 2 && defined(_C_BOOL)
           case _C_BOOL:
             {
               _Bool     v;
@@ -1110,7 +1109,6 @@ GSObjCGetVal(NSObject *self, const char *key, SEL sel,
               val = [NSNumber numberWithBool: (BOOL)v];
             }
             break;
-#endif
 #endif
 
 	  case _C_SHT:
@@ -1557,8 +1555,7 @@ GSObjCSetVal(NSObject *self, const char *key, id val, SEL sel,
 	    }
 	    break;
 
-#if __GNUC__ != 2
-#ifdef  _C_BOOL
+#if __GNUC__ != 2 && defined(_C_BOOL)
           case _C_BOOL:
             {
               _Bool     v = (_Bool)[val boolValue];
@@ -1578,7 +1575,6 @@ GSObjCSetVal(NSObject *self, const char *key, id val, SEL sel,
                 }
             }
             break;
-#endif
 #endif
 
 	  case _C_SHT:
diff --git a/Source/GSFFCallInvocation.m b/Source/GSFFCallInvocation.m
index 7dc3303e7..b29d5e057 100644
--- a/Source/GSFFCallInvocation.m
+++ b/Source/GSFFCallInvocation.m
@@ -425,7 +425,7 @@ gs_sel_type_to_callback_type (const char *sel_type,
       case _C_DBL:
 	vatype->type = __VAdouble;
 	break;
-#if __GNUC__ != 2
+#ifdef  _C_BOOL
       case _C_BOOL:
 	vatype->type = __VAuchar;
 	break;
@@ -614,7 +614,7 @@ GSFFCallInvokeWithTargetAndImp(NSInvocation *_inv, id anObject, IMP imp)
       CASE_TYPE(_C_ULNG_LNG, unsigned long long, av_start_ulonglong)
       CASE_TYPE(_C_FLT,  float, av_start_float)
       CASE_TYPE(_C_DBL,  double, av_start_double)
-#if __GNUC__ != 2
+#ifdef  _C_BOOL
       CASE_TYPE(_C_BOOL, _Bool, av_start_uchar)
 #endif
 
@@ -719,7 +719,7 @@ GSFFCallInvokeWithTargetAndImp(NSInvocation *_inv, id anObject, IMP imp)
           CASE_TYPE(_C_ULNG_LNG, unsigned long long, av_ulonglong)
           CASE_TYPE(_C_FLT,  float, av_float)
           CASE_TYPE(_C_DBL,  double, av_double)
-#if __GNUC__ != 2
+#ifdef  _C_BOOL
           CASE_TYPE(_C_BOOL, _Bool, av_uchar)
 #endif
 	
@@ -1057,7 +1057,7 @@ GSInvocationCallback (void *callback_data, va_alist args)
 	  CASE_TYPE(_C_ULNG_LNG, unsigned long long, va_arg_ulonglong)
 	  CASE_TYPE(_C_FLT,  float, va_arg_float)
 	  CASE_TYPE(_C_DBL,  double, va_arg_double)
-#if __GNUC__ != 2
+#ifdef  _C_BOOL
 	  CASE_TYPE(_C_BOOL,  _Bool, va_arg_uchar)
 #endif
 	
@@ -1120,7 +1120,7 @@ GSInvocationCallback (void *callback_data, va_alist args)
       CASE_TYPE(_C_ULNG_LNG, unsigned long long, va_return_ulonglong)
       CASE_TYPE(_C_FLT,  float, va_return_float)
       CASE_TYPE(_C_DBL,  double, va_return_double)
-#if __GNUC__ != 2
+#ifdef  _C_BOOL
       CASE_TYPE(_C_BOOL, _Bool, va_return_uchar)
 #endif
 
diff --git a/Source/GSValue.m b/Source/GSValue.m
index 7777d76f5..a70b8d436 100644
--- a/Source/GSValue.m
+++ b/Source/GSValue.m
@@ -61,7 +61,7 @@ typeSize(const char* type)
       case _C_ULNG_LNG:	return sizeof(unsigned long long);
       case _C_FLT:	return sizeof(float);
       case _C_DBL:	return sizeof(double);
-#if __GNUC__ != 2
+#ifdef  _C_BOOL
       case _C_BOOL:	return sizeof(_Bool);
 #endif
       case _C_PTR:	return sizeof(void*);
diff --git a/Source/NSArchiver.m b/Source/NSArchiver.m
index 013c9a269..b1f052499 100644
--- a/Source/NSArchiver.m
+++ b/Source/NSArchiver.m
@@ -310,7 +310,7 @@ static Class	NSMutableDataMallocClass;
       case _C_ULNG_LNG:	info = _GSC_ULNG_LNG | _GSC_S_LNG_LNG;	break;
       case _C_FLT:	info = _GSC_FLT;	break;
       case _C_DBL:	info = _GSC_DBL;	break;
-#if __GNUC__ != 2
+#ifdef  _C_BOOL
       case _C_BOOL:	info = _GSC_BOOL;	break;
 #endif
       default:		info = _GSC_NONE;	break;
@@ -684,7 +684,7 @@ static Class	NSMutableDataMallocClass;
 	(*_serImp)(_dst, serSel, (void*)buf, @encode(double), nil);
 	return;
 
-#if __GNUC__ != 2
+#ifdef  _C_BOOL
       case _C_BOOL:
 	(*_tagImp)(_dst, tagSel, _GSC_BOOL);
 	(*_serImp)(_dst, serSel, (void*)buf, @encode(_Bool), nil);
diff --git a/Source/NSData.m b/Source/NSData.m
index 393b08c43..b10195d11 100644
--- a/Source/NSData.m
+++ b/Source/NSData.m
@@ -1385,7 +1385,7 @@ failure:
 	  *(double*)data = NSSwapBigDoubleToHost(nd);
 	  return;
 	}
-#if __GNUC__ != 2
+#ifdef  _C_BOOL
       case _C_BOOL:
 	{
 	  [self deserializeBytes: data
@@ -2672,7 +2672,7 @@ failure:
 	  [self appendBytes: &nd length: sizeof(NSSwappedDouble)];
 	  return;
 	}
-#if __GNUC__ != 2
+#ifdef  _C_BOOL
       case _C_BOOL:
 	[self appendBytes: data length: sizeof(_Bool)];
 	return;
@@ -3159,7 +3159,7 @@ getBytes(void* dst, void* src, unsigned len, unsigned limit, unsigned *pos)
 	  *(double*)data = NSSwapBigDoubleToHost(nd);
 	  return;
 	}
-#if __GNUC__ != 2
+#ifdef  _C_BOOL
       case _C_BOOL:
 	{
 	  getBytes(data, bytes, sizeof(_Bool), length, cursor);
@@ -4000,7 +4000,7 @@ getBytes(void* dst, void* src, unsigned len, unsigned limit, unsigned *pos)
 	  (*appendImp)(self, appendSel, &nd, sizeof(NSSwappedDouble));
 	  return;
 	}
-#if __GNUC__ != 2
+#ifdef  _C_BOOL
       case _C_BOOL:
 	(*appendImp)(self, appendSel, data, sizeof(_Bool));
 	return;
diff --git a/Source/NSDecimalNumber.m b/Source/NSDecimalNumber.m
index 178e83c03..47ededb2a 100644
--- a/Source/NSDecimalNumber.m
+++ b/Source/NSDecimalNumber.m
@@ -324,7 +324,7 @@ static NSDecimalNumber *one;
 	llval = (long long)v;
 	break;
       }
-#if __GNUC__ != 2
+#ifdef  _C_BOOL
     case _C_BOOL:
       {
 	llval = (long long)((*(unsigned char *)value == 0) ? 0 : 1);
diff --git a/Source/NSKeyValueObserving.m b/Source/NSKeyValueObserving.m
index 1d10a2ef6..1eb02de76 100644
--- a/Source/NSKeyValueObserving.m
+++ b/Source/NSKeyValueObserving.m
@@ -573,7 +573,7 @@ cifframe_callback(ffi_cif *cif, void *retp, void **args, void *user)
                 imp = [[GSKVOSetter class]
                   instanceMethodForSelector: @selector(setterDouble:)];
                 break;
-#if __GNUC__ != 2
+#ifdef  _C_BOOL
               case _C_BOOL:
                 imp = [[GSKVOSetter class]
                   instanceMethodForSelector: @selector(setterChar:)];
diff --git a/Source/NSKeyedArchiver.m b/Source/NSKeyedArchiver.m
index 2b6754190..2216c478e 100644
--- a/Source/NSKeyedArchiver.m
+++ b/Source/NSKeyedArchiver.m
@@ -792,7 +792,7 @@ static NSDictionary *makeReference(unsigned ref)
 	[_enc setObject: o forKey: aKey];
 	return;
 
-#if __GNUC__ != 2
+#ifdef  _C_BOOL
       case _C_BOOL:
 	o = [NSNumber numberWithInt: (NSInteger)*(_Bool*)address];
 	[_enc setObject: o forKey: aKey];
diff --git a/Source/NSKeyedUnarchiver.m b/Source/NSKeyedUnarchiver.m
index 4192225bb..d1dd8b3df 100644
--- a/Source/NSKeyedUnarchiver.m
+++ b/Source/NSKeyedUnarchiver.m
@@ -748,7 +748,7 @@ static NSMapTable	*globalClassMap = 0;
 	*(double*)address = [o doubleValue];
 	return;
 
-#if __GNUC__ != 2
+#ifdef  _C_BOOL
       case _C_BOOL:
 	*(_Bool*)address = (_Bool)[o unsignedCharValue];
 	return;
diff --git a/Source/NSMethodSignature.m b/Source/NSMethodSignature.m
index 93ba7e0bf..de7a71543 100644
--- a/Source/NSMethodSignature.m
+++ b/Source/NSMethodSignature.m
@@ -332,7 +332,7 @@ next_arg(const char *typePtr, NSArgumentInfo *info, char *outTypes)
 	info->align = __alignof__(char*);
 	break;
 
-#if __GNUC__ != 2
+#ifdef  _C_BOOL
       case _C_BOOL:
 	info->size = sizeof(_Bool);
 	info->align = __alignof__(_Bool);
diff --git a/Source/NSNumberFormatter.m b/Source/NSNumberFormatter.m
index 7495ea1d1..2b5d1716f 100644
--- a/Source/NSNumberFormatter.m
+++ b/Source/NSNumberFormatter.m
@@ -1100,7 +1100,7 @@ static NSUInteger _defaultBehavior = NSNumberFormatterBehavior10_4;
            * don't think it matters, because we don't bother with anything
            * smaller than int for NSNumbers
 	   */
-#if	defined(_C_BOOL)
+#ifdef  _C_BOOL
           case _C_BOOL:
             STRING_FROM_NUMBER(unum_format, (int)[anObject boolValue]);
             break;
diff --git a/Source/NSPortCoder.m b/Source/NSPortCoder.m
index 5a9684311..b3cc44d48 100644
--- a/Source/NSPortCoder.m
+++ b/Source/NSPortCoder.m
@@ -129,7 +129,9 @@ typeToName1(char type)
       case _C_CHARPTR:	return "cstring";
       case _C_ARY_B:	return "array";
       case _C_STRUCT_B:	return "struct";
+#ifdef  _C_BOOL
       case _C_BOOL:	return "_Bool";
+#endif
       default:
 	{
 	  static char	buf1[32];
@@ -220,7 +222,11 @@ static char	type_map[32] = {
 #endif
   _C_FLT,
   _C_DBL,
+#ifdef  _C_BOOL
   _C_BOOL,
+#else
+  0,
+#endif
   0,
   0,
   _C_ID,
@@ -517,7 +523,9 @@ static unsigned	encodingVersion;
 #endif
       case _C_FLT:	info = _GSC_FLT; break;
       case _C_DBL:	info = _GSC_DBL; break;
+#ifdef  _C_BOOL
       case _C_BOOL:	info = _GSC_BOOL; break;
+#endif
       default:		info = _GSC_NONE; break;
     }
 
@@ -1214,7 +1222,9 @@ static unsigned	encodingVersion;
       case _C_ULNG_LNG:	info = _GSC_ULNG_LNG | _GSC_S_LNG_LNG;	break;
       case _C_FLT:	info = _GSC_FLT;	break;
       case _C_DBL:	info = _GSC_DBL;	break;
+#ifdef  _C_BOOL
       case _C_BOOL:	info = _GSC_BOOL;	break;
+#endif
       default:		info = _GSC_NONE;	break;
     }
 
@@ -1813,7 +1823,7 @@ static unsigned	encodingVersion;
 	(*_eSerImp)(_dst, eSerSel, (void*)buf, @encode(double), nil);
 	return;
 
-#if __GNUC__ != 2
+#ifdef  _C_BOOL
       case _C_BOOL:
 	(*_eTagImp)(_dst, eTagSel, _GSC_BOOL);
 	(*_eSerImp)(_dst, eSerSel, (void*)buf, @encode(_Bool), nil);
diff --git a/Source/NSUnarchiver.m b/Source/NSUnarchiver.m
index e62b5adfc..b790d525a 100644
--- a/Source/NSUnarchiver.m
+++ b/Source/NSUnarchiver.m
@@ -78,7 +78,9 @@ typeToName1(char type)
       case _C_ULNG_LNG:	return "unsigned long long";
       case _C_FLT:	return "float";
       case _C_DBL:	return "double";
+#ifdef  _C_BOOL
       case _C_BOOL:	return "_Bool";
+#endif
       case _C_PTR:	return "pointer";
       case _C_CHARPTR:	return "cstring";
       case _C_ARY_B:	return "array";
@@ -168,7 +170,11 @@ static char	type_map[32] = {
   _C_ULNG_LNG,
   _C_FLT,
   _C_DBL,
+#ifdef  _C_BOOL
   _C_BOOL,
+#else
+  0,
+#endif
   0,
   0,
   _C_ID,
@@ -610,7 +616,9 @@ static unsigned	encodingVersion;
       case _C_ULNG_LNG:	info = _GSC_ULNG_LNG; break;
       case _C_FLT:	info = _GSC_FLT; break;
       case _C_DBL:	info = _GSC_DBL; break;
+#ifdef  _C_BOOL
       case _C_BOOL:	info = _GSC_BOOL; break;
+#endif
       default:		info = _GSC_NONE; break;
     }
 
diff --git a/Source/cifframe.m b/Source/cifframe.m
index ec38c2399..c4d37695e 100644
--- a/Source/cifframe.m
+++ b/Source/cifframe.m
@@ -540,7 +540,7 @@ cifframe_type(const char *typePtr, const char **advance)
 
     case _C_VOID: ftype = &ffi_type_void;
       break;
-#if __GNUC__ != 2
+#if __GNUC__ != 2 && defined(_C_BOOL)
     case _C_BOOL: ftype = &ffi_type_uchar;
       break;
 #endif