diff --git a/kern/monitor.c b/kern/monitor.c
index 1e626e2..528671c 100644
--- a/kern/monitor.c
+++ b/kern/monitor.c
@@ -30,7 +30,9 @@ static struct Command commands[] = {
 	{ "help", "Display this list of commands", mon_help },
 	{ "kerninfo", "Display information about the kernel", mon_kerninfo },
 	{ "backtrace", "Display current backtrace", mon_backtrace },
-	{ "showmappings", "Display the physical mappings for range", mon_showmappings }
+	{ "showmappings", "Display the physical mappings for range", mon_showmappings },
+	{ "mperms", "Change the permissions of a memory range", mon_mperms }
+	
 };
 
 /***** Implementations of basic kernel monitor commands *****/
@@ -104,21 +106,26 @@ decode_pte_perms(pte_t pte, char* buffer) {
 	return buffer;
 }
 
+void
+get_pagebounds(char* one, char* two, uintptr_t* pone, uintptr_t* ptwo) {
+	long from = strtol(one, NULL, 0);
+	long to = strtol(two, NULL, 0);
+	*pone = ROUNDDOWN(from, PGSIZE);
+	*ptwo = ROUNDUP(to, PGSIZE);
+	if(*pone != from) cprintf(ACOL_WARN("Aligning start address %p down to %p\n"),
+		from, *pone);
+	if(*ptwo != to) cprintf(ACOL_WARN("Aligning end address %p up to %p\n"),
+		to, *ptwo);
+}
+
 int
 mon_showmappings(int argc, char** argv, struct Trapframe* tf) {
 	EXPECT_ARGS(2, argc);
-	long from = strtol(argv[1], NULL, 0);
-	long to = strtol(argv[2], NULL, 0);
-
-	uintptr_t va_start = ROUNDDOWN(from, PGSIZE);
-	uintptr_t va_end = ROUNDUP(to, PGSIZE);
-	if(va_start != from) cprintf(ACOL_WARN("Aligning start address %p down to %p\n"),
-		from, va_start);
-	if(va_end != to) cprintf(ACOL_WARN("Aligning end address %p up to %p\n"),
-		to, va_end);
-
+	uintptr_t va_start, va_end;
 	char buffer[3] = {0};
 
+	get_pagebounds(argv[1], argv[2], &va_start, &va_end);
+
 	if(va_start == va_end) va_end += PGSIZE;
 	while(va_start < va_end) {
 		pte_t* pte = pgdir_walk(kern_pgdir, (const void*) va_start, 0);
@@ -137,6 +144,49 @@ mon_showmappings(int argc, char** argv, struct Trapframe* tf) {
 	return 0;
 }
 
+int mon_mperms(int argc, char** argv, struct Trapframe* tf) {
+	EXPECT_ARGS(3, argc);
+	pte_t perms = 0;
+	enum {
+		PERM_ADD,
+		PERM_REMOVE,
+		PERM_SET
+	} pmode;
+
+	const char* str = argv[1];
+	if(str[0] == '+') { pmode = PERM_ADD; str++; }
+	else if(str[0] == '-') { pmode = PERM_REMOVE; str++; }
+	else pmode = PERM_SET;
+
+	while(*str) {
+		if(*str == 'w') perms |= PTE_W;
+		else if(*str == 'u') perms |= PTE_U;
+		else {
+			cprintf(ACOL_ERR("Unknown permission character %c\n"), *str);
+			return 1;
+		}
+		str++;
+	}
+
+	uintptr_t va_start, va_end;
+	get_pagebounds(argv[2], argv[3], &va_start, &va_end);
+	if(va_start == va_end) va_end += PGSIZE;
+	while(va_start < va_end) {
+		pte_t* pte = pgdir_walk(kern_pgdir, (void*) va_start, 0);
+		if(!pte || !(*pte & PTE_P)) { va_start += PGSIZE; continue; }
+		
+		if(pmode == PERM_ADD) {
+			*pte |= perms;
+		} else if(pmode == PERM_REMOVE) {
+			*pte &= ~perms;
+		} else if(pmode == PERM_SET) {
+			*pte = PTE_ADDR(*pte) | perms | PTE_P;
+		}
+		va_start += PGSIZE;
+	}
+
+	return 0;
+}
 
 /***** Kernel monitor command interpreter *****/