Index: src/OFMethodSignature.h
==================================================================
--- src/OFMethodSignature.h
+++ src/OFMethodSignature.h
@@ -26,11 +26,11 @@
  * @brief A class for parsing type encodings and accessing them.
  */
 @interface OFMethodSignature: OFObject
 {
 	char *_types;
-	OFMutableData *_typesPointers;
+	OFMutableData *_typesPointers, *_offsets;
 }
 
 /*!
  * The number of arguments of the method.
  */
@@ -39,10 +39,17 @@
 /*!
  * The return type of the method.
  */
 @property (readonly, nonatomic) const char *methodReturnType;
 
+/*!
+ * The size of the arguments on the stack frame.
+ *
+ * @note This is platform-dependent!
+ */
+@property (readonly, nonatomic) size_t frameLength;
+
 /*!
  * @brief Creates a new, autoreleased OFMethodSignature with the specified
  *	  ObjC types.
  *
  * @param types The ObjC types of the method
@@ -60,12 +67,24 @@
 - initWithObjCTypes: (const char *)types;
 
 /*!
  * @brief Returns the ObjC type for the argument at the specified index.
  *
- * @param index The index for which to return the ObjC type
+ * @param index The index of the argument for which to return the ObjC type
  * @return The ObjC type for the argument at the specified index
  */
 - (const char *)argumentTypeAtIndex: (size_t)index;
+
+/*!
+ * @brief Returns the offset on the stack frame of the argument at the
+ *	  specified index.
+ *
+ * @note This is platform-dependent!
+ *
+ * @param index The index of the argument for which to return the offset
+ * @returns The offset on the stack frame of the argument at the
+ *	    specified index
+ */
+- (size_t)argumentOffsetAtIndex: (size_t)index;
 @end
 
 OF_ASSUME_NONNULL_END

Index: src/OFMethodSignature.m
==================================================================
--- src/OFMethodSignature.m
+++ src/OFMethodSignature.m
@@ -49,23 +49,30 @@
 		_types = [self allocMemoryWithSize: length + 1];
 		memcpy(_types, types, length);
 
 		_typesPointers = [[OFMutableData alloc]
 		    initWithItemSize: sizeof(char *)];
+		_offsets = [[OFMutableData alloc]
+		    initWithItemSize: sizeof(size_t)];
 
 		last = _types;
 		for (size_t i = 0; i < length; i++) {
 			if (isdigit(_types[i])) {
+				size_t offset = _types[i] - '0';
+
 				if (last == _types + i)
 					@throw [OFInvalidFormatException
 					    exception];
 
 				_types[i] = '\0';
 				[_typesPointers addItem: &last];
 
 				i++;
-				for (; i < length && isdigit(_types[i]); i++);
+				for (; i < length && isdigit(_types[i]); i++)
+					offset = offset * 10 + _types[i] - '0';
+
+				[_offsets addItem: &offset];
 
 				last = _types + i;
 				i--;
 			} else if (_types[i] == '{') {
 				size_t depth = 0;
@@ -111,10 +118,11 @@
 }
 
 - (void)dealloc
 {
 	[_typesPointers release];
+	[_offsets release];
 
 	[super dealloc];
 }
 
 - (size_t)numberOfArguments
@@ -124,11 +132,21 @@
 
 - (const char *)methodReturnType
 {
 	return *(const char **)[_typesPointers firstItem];
 }
+
+- (size_t)frameLength
+{
+	return *(size_t *)[_offsets firstItem];
+}
 
 - (const char *)argumentTypeAtIndex: (size_t)index
 {
 	return *(const char **)[_typesPointers itemAtIndex: index + 1];
 }
+
+- (size_t)argumentOffsetAtIndex: (size_t)index
+{
+	return *(size_t *)[_offsets itemAtIndex: index + 1];
+}
 @end

Index: tests/OFMethodSignatureTests.m
==================================================================
--- tests/OFMethodSignatureTests.m
+++ tests/OFMethodSignatureTests.m
@@ -38,11 +38,15 @@
 	    "i28@0:8S16*20"]) && [ms numberOfArguments] == 4 &&
 	    strcmp([ms methodReturnType], "i") == 0 &&
 	    strcmp([ms argumentTypeAtIndex: 0], "@") == 0 &&
 	    strcmp([ms argumentTypeAtIndex: 1], ":") == 0 &&
 	    strcmp([ms argumentTypeAtIndex: 2], "S") == 0 &&
-	    strcmp([ms argumentTypeAtIndex: 3], "*") == 0)
+	    strcmp([ms argumentTypeAtIndex: 3], "*") == 0 &&
+	    [ms frameLength] == 28 && [ms argumentOffsetAtIndex: 0] == 0 &&
+	    [ms argumentOffsetAtIndex: 1] == 8 &&
+	    [ms argumentOffsetAtIndex: 2] == 16 &&
+	    [ms argumentOffsetAtIndex: 3] == 20)
 
 	TEST(@"-[signatureWithObjCTypes:] #2",
 	    (ms = [OFMethodSignature signatureWithObjCTypes:
 	    "{s0=csi(u1={s2=iii{s3=(u4=ic^v*)}})}24@0:8"
 	    "^{s0=csi(u1={s2=iii{s3=(u4=ic^v*)}})}16"]) &&
@@ -50,11 +54,14 @@
 	    strcmp([ms methodReturnType],
 	    "{s0=csi(u1={s2=iii{s3=(u4=ic^v*)}})}") == 0 &&
 	    strcmp([ms argumentTypeAtIndex: 0], "@") == 0 &&
 	    strcmp([ms argumentTypeAtIndex: 1], ":") == 0 &&
 	    strcmp([ms argumentTypeAtIndex: 2],
-	    "^{s0=csi(u1={s2=iii{s3=(u4=ic^v*)}})}") == 0)
+	    "^{s0=csi(u1={s2=iii{s3=(u4=ic^v*)}})}") == 0 &&
+	    [ms frameLength] == 24 && [ms argumentOffsetAtIndex: 0] == 0 &&
+	    [ms argumentOffsetAtIndex: 1] == 8 &&
+	    [ms argumentOffsetAtIndex: 2] == 16)
 
 	EXPECT_EXCEPTION(@"-[signatureWithObjCTypes:] #3",
 	    OFInvalidFormatException,
 	    [OFMethodSignature signatureWithObjCTypes: "{ii"])