diff --git a/src/system/boot/platform/openfirmware/arch/ppc/mmu.cpp b/src/system/boot/platform/openfirmware/arch/ppc/mmu.cpp
index b365b9e23d..2979da7a96 100644
--- a/src/system/boot/platform/openfirmware/arch/ppc/mmu.cpp
+++ b/src/system/boot/platform/openfirmware/arch/ppc/mmu.cpp
@@ -654,7 +654,8 @@ arch_set_callback(void)
 	// instead of maintaining it itself
 
 	void *oldCallback = NULL;
-	if (of_call_method("set-callback", 1, 1, &callback, &oldCallback) == OF_FAILED) {
+	if (of_call_client_function("set-callback", 1, 1, &callback, &oldCallback)
+			== OF_FAILED) {
 		puts("set-callback failed!");
 		return B_ERROR;
 	}
diff --git a/src/system/boot/platform/openfirmware/openfirmware.c b/src/system/boot/platform/openfirmware/openfirmware.c
index 1f958131c3..44350f0355 100644
--- a/src/system/boot/platform/openfirmware/openfirmware.c
+++ b/src/system/boot/platform/openfirmware/openfirmware.c
@@ -27,7 +27,7 @@ of_init(int (*openFirmwareEntry)(void *))
 
 
 int
-of_call_method(const char *method, int numArgs, int numReturns, ...)
+of_call_client_function(const char *method, int numArgs, int numReturns, ...)
 {
 	struct {
 		const char	*name;
@@ -83,7 +83,58 @@ of_interpret(const char *command, int numArgs, int numReturns, ...)
 			// stack_result items."
 		const char	*command;
 		void		*args[13];
-	} args = {"interpret", numArgs + 1, numReturns, command};
+	} args = {"interpret", numArgs + 1, numReturns + 1, command};
+	va_list list;
+	int i;
+
+	// iterate over all arguments and copy them into the
+	// structure passed over to the OpenFirmware
+
+	va_start(list, numReturns);
+	for (i = 0; i < numArgs; i++) {
+		// copy args
+		args.args[i] = (void *)va_arg(list, void *);
+	}
+	for (i = numArgs; i < numArgs + numReturns + 1; i++) {
+		// clear return values
+		args.args[i] = NULL;
+	}
+
+	// args.args[numArgs] is the "catch-result" return value
+	if (gCallOpenFirmware(&args) == OF_FAILED || args.args[numArgs])
+		return OF_FAILED;
+
+	if (numReturns > 0) {
+		// copy return values over to the provided location
+	
+		for (i = numArgs + 1; i < numArgs + 1 + numReturns; i++) {
+			void **store = va_arg(list, void **);
+			if (store)
+				*store = args.args[i];
+		}
+	}
+	va_end(list);
+
+	return 0;
+}
+
+
+int
+of_call_method(int handle, const char *method, int numArgs, int numReturns, ...)
+{
+	struct {
+		const char	*name;
+		int			num_args;
+		int			num_returns;
+			// "IN:	[string] method, ihandle, stack_arg1, ..., stack_argP
+			// OUT:	catch-result, stack_result1, ..., stack_resultQ
+			// [...]
+			// An implementation shall allow at least six stack_arg and six
+			// stack_result items."
+		const char	*method;
+		int			handle;
+		void		*args[13];
+	} args = {"call-method", numArgs + 2, numReturns + 1, method, handle};
 	va_list list;
 	int i;
 
diff --git a/src/system/boot/platform/openfirmware/openfirmware.h b/src/system/boot/platform/openfirmware/openfirmware.h
index 75fe63371c..9e75fc10e6 100644
--- a/src/system/boot/platform/openfirmware/openfirmware.h
+++ b/src/system/boot/platform/openfirmware/openfirmware.h
@@ -46,9 +46,12 @@ extern int of_peer(int node);
 extern int of_parent(int node);
 extern int of_instance_to_path(int instance, char *pathBuffer, int bufferSize);
 extern int of_instance_to_package(int instance);
-extern int of_getprop(int package, const char *property, void *buffer, int bufferSize);
-extern int of_setprop(int package, const char *property, const void *buffer, int bufferSize);
-extern int of_nextprop(int package, const char *previousProperty, char *nextProperty);
+extern int of_getprop(int package, const char *property, void *buffer,
+	int bufferSize);
+extern int of_setprop(int package, const char *property, const void *buffer,
+	int bufferSize);
+extern int of_nextprop(int package, const char *previousProperty,
+	char *nextProperty);
 extern int of_getproplen(int package, const char *property);
 extern int of_package_to_path(int package, char *pathBuffer, int bufferSize);
 
@@ -64,8 +67,11 @@ extern int of_release(void *virtualAddress, int size);
 extern void *of_claim(void *virtualAddress, int size, int align);
 
 /* misc functions */
-extern int of_call_method(const char *method, int numArgs, int numReturns, ...);
+extern int of_call_client_function(const char *method, int numArgs,
+	int numReturns, ...);
 extern int of_interpret(const char *command, int numArgs, int numReturns, ...);
+extern int of_call_method(int handle, const char *method, int numArgs,
+	int numReturns, ...);
 extern int of_test(const char *service);
 extern int of_milliseconds(void);
 extern void of_exit(void);