diff --git a/Source/GSString.m b/Source/GSString.m
index 41630449e..17b6e3291 100644
--- a/Source/GSString.m
+++ b/Source/GSString.m
@@ -1155,11 +1155,6 @@ compare_c(GSStr self, NSString *aString, unsigned mask, NSRange aRange)
 {
   Class	c;
 
-  if (aString == nil)
-    [NSException raise: NSInvalidArgumentException format: @"compare with nil"];
-  if (GSObjCIsInstance(aString) == NO)
-    return strCompCsNs((id)self, aString, mask, aRange);
-
   c = GSObjCClass(aString);
   if (GSObjCIsKindOf(c, GSUnicodeStringClass) == YES
     || (c == GSMutableStringClass && ((GSStr)aString)->_flags.wide == 1))
@@ -1177,11 +1172,6 @@ compare_u(GSStr self, NSString *aString, unsigned mask, NSRange aRange)
 {
   Class	c;
 
-  if (aString == nil)
-    [NSException raise: NSInvalidArgumentException format: @"compare with nil"];
-  if (GSObjCIsInstance(aString) == NO)
-    return strCompUsNs((id)self, aString, mask, aRange);
-
   c = GSObjCClass(aString);
   if (GSObjCIsKindOf(c, GSUnicodeStringClass)
     || (c == GSMutableStringClass && ((GSStr)aString)->_flags.wide == 1))
@@ -2830,6 +2820,15 @@ transmute(GSStr self, NSString *aString)
 		       options: (unsigned int)mask
 			 range: (NSRange)aRange
 {
+  GS_RANGE_CHECK(aRange, _count);
+  if (aString == nil)
+    [NSException raise: NSInvalidArgumentException
+		format: @"[%@ -%@] nil string argument",
+      NSStringFromClass([self class]), NSStringFromSelector(_cmd)];
+  if (GSObjCIsInstance(aString) == NO)
+    [NSException raise: NSInvalidArgumentException
+		format: @"[%@ -%@] not a string argument",
+      NSStringFromClass([self class]), NSStringFromSelector(_cmd)];
   return compare_c((GSStr)self, aString, mask, aRange);
 }
 
@@ -3151,6 +3150,15 @@ agree, create a new GSCInlineString otherwise.
 		       options: (unsigned int)mask
 			 range: (NSRange)aRange
 {
+  GS_RANGE_CHECK(aRange, _count);
+  if (aString == nil)
+    [NSException raise: NSInvalidArgumentException
+		format: @"[%@ -%@] nil string argument",
+      NSStringFromClass([self class]), NSStringFromSelector(_cmd)];
+  if (GSObjCIsInstance(aString) == NO)
+    [NSException raise: NSInvalidArgumentException
+		format: @"[%@ -%@] not a string argument",
+      NSStringFromClass([self class]), NSStringFromSelector(_cmd)];
   return compare_u((GSStr)self, aString, mask, aRange);
 }
 
@@ -3543,6 +3551,15 @@ agree, create a new GSUnicodeInlineString otherwise.
 		       options: (unsigned int)mask
 			 range: (NSRange)aRange
 {
+  GS_RANGE_CHECK(aRange, _count);
+  if (aString == nil)
+    [NSException raise: NSInvalidArgumentException
+		format: @"[%@ -%@] nil string argument",
+      NSStringFromClass([self class]), NSStringFromSelector(_cmd)];
+  if (GSObjCIsInstance(aString) == NO)
+    [NSException raise: NSInvalidArgumentException
+		format: @"[%@ -%@] not a string argument",
+      NSStringFromClass([self class]), NSStringFromSelector(_cmd)];
   if (_flags.wide == 1)
     return compare_u((GSStr)self, aString, mask, aRange);
   else
@@ -4662,6 +4679,15 @@ NSAssert(_flags.free == 1 && _zone != 0, NSInternalInconsistencyException);
 		       options: (unsigned int)mask
 			 range: (NSRange)aRange
 {
+  GS_RANGE_CHECK(aRange, ((GSStr)_parent)->_count);
+  if (aString == nil)
+    [NSException raise: NSInvalidArgumentException
+		format: @"[%@ -%@] nil string argument",
+      NSStringFromClass([self class]), NSStringFromSelector(_cmd)];
+  if (GSObjCIsInstance(aString) == NO)
+    [NSException raise: NSInvalidArgumentException
+		format: @"[%@ -%@] not a string argument",
+      NSStringFromClass([self class]), NSStringFromSelector(_cmd)];
   if (((GSStr)_parent)->_flags.wide == 1)
     return compare_u((GSStr)_parent, aString, mask, aRange);
   else
diff --git a/Source/NSString.m b/Source/NSString.m
index aa04d99a5..90e2f9819 100644
--- a/Source/NSString.m
+++ b/Source/NSString.m
@@ -1918,6 +1918,7 @@ handle_printf_atsign (FILE *stream,
 		       options: (unsigned int)mask
 			 range: (NSRange)aRange
 {
+  GS_RANGE_CHECK(aRange, [self length]);
   if (aString == nil)
     [NSException raise: NSInvalidArgumentException format: @"compare with nil"];
   return strCompNsNs(self, aString, mask, aRange);