diff --git a/include/l4/glue/arm/memory.h b/include/l4/glue/arm/memory.h
index 0d8d389..4c27416 100644
--- a/include/l4/glue/arm/memory.h
+++ b/include/l4/glue/arm/memory.h
@@ -111,8 +111,8 @@ void add_mapping_pgd(unsigned int paddr, unsigned int vaddr,
 		     pgd_table_t *pgd);
 void add_mapping(unsigned int paddr, unsigned int vaddr,
 		 unsigned int size, unsigned int flags);
-void remove_mapping(unsigned long vaddr);
-void remove_mapping_pgd(unsigned long vaddr, pgd_table_t *pgd);
+int remove_mapping(unsigned long vaddr);
+int remove_mapping_pgd(unsigned long vaddr, pgd_table_t *pgd);
 void prealloc_phys_pagedesc(void);
 
 int check_mapping_pgd(unsigned long vaddr, unsigned long size,
diff --git a/src/api/space.c b/src/api/space.c
index 7564c21..c3248e7 100644
--- a/src/api/space.c
+++ b/src/api/space.c
@@ -40,26 +40,30 @@ found:
 	return 0;
 }
 
-
+/*
+ * Unmaps given range from given task. If the complete range is unmapped
+ * sucessfully, returns 0. If part of the range was found to be already
+ * unmapped, returns -1. This is may or may not be an error.
+ */
 int sys_unmap(syscall_context_t *regs)
 {
-	unsigned long virt = regs->r0;
+	unsigned long virtual = regs->r0;
 	unsigned long npages = regs->r1;
 	unsigned int tid = regs->r2;
 	struct ktcb *target;
+	int ret, retval;
 
-	if (tid == current->tid) { /* The easiest case */
+	if (tid == current->tid)
 		target = current;
-		goto found;
-	} else 	/* else search the tcb from its hash list */
-		if ((target = find_task(tid)))
-			goto found;
-	BUG();
-	return -EINVAL;
-found:
-	for (int i = 0; i < npages; i++)
-		remove_mapping_pgd(virt, target->pgd);
+	else if (!(target = find_task(tid)))
+		return -ESRCH;
 
-	return 0;
+	for (int i = 0; i < npages; i++) {
+		ret = remove_mapping_pgd(virtual + i * PAGE_SIZE, target->pgd);
+		if (ret)
+			retval = ret;
+	}
+
+	return retval;
 }
 
diff --git a/src/arch/arm/v5/mm.c b/src/arch/arm/v5/mm.c
index db61a86..765ea31 100644
--- a/src/arch/arm/v5/mm.c
+++ b/src/arch/arm/v5/mm.c
@@ -274,31 +274,38 @@ int check_mapping(unsigned long vaddr, unsigned long size,
 }
 
 /* FIXME: Empty PMDs should be returned here !!! */
-void __remove_mapping(pmd_table_t *pmd, unsigned long vaddr)
+int __remove_mapping(pmd_table_t *pmd, unsigned long vaddr)
 {
 	pmd_t pmd_i = PMD_INDEX(vaddr);
+	int ret;
 
 	switch (pmd->entry[pmd_i] & PMD_TYPE_MASK) {
+		case PMD_TYPE_FAULT:
+			ret = -1;
+			break;
 		case PMD_TYPE_LARGE:
 			pmd->entry[pmd_i] = 0;
 			pmd->entry[pmd_i] |= PMD_TYPE_FAULT;
+			ret = 0;
 			break;
 		case PMD_TYPE_SMALL:
 			pmd->entry[pmd_i] = 0;
 			pmd->entry[pmd_i] |= PMD_TYPE_FAULT;
+			ret = 0;
 			break;
 		default:
 			printk("Unknown page mapping in pmd. Assuming bug.\n");
 			BUG();
 	}
-	return;
+	return ret;
 }
 
-void remove_mapping_pgd(unsigned long vaddr, pgd_table_t *pgd)
+int remove_mapping_pgd(unsigned long vaddr, pgd_table_t *pgd)
 {
 	pgd_t pgd_i = PGD_INDEX(vaddr);
 	pmd_table_t *pmd;
 	pmd_t pmd_i;
+	int ret;
 
 	/*
 	 * Clean the cache to main memory before removing the mapping. Otherwise
@@ -321,20 +328,19 @@ void remove_mapping_pgd(unsigned long vaddr, pgd_table_t *pgd)
 			      phys_to_virt((pgd->entry[pgd_i]
 					   & PGD_COARSE_ALIGN_MASK));
 			pmd_i = PMD_INDEX(vaddr);
-			__remove_mapping(pmd, vaddr);
+			ret = __remove_mapping(pmd, vaddr);
 			break;
 
 		case PGD_TYPE_FAULT:
-			dprintk("Attempting to remove fault mapping. "
-				"Assuming bug.\n", vaddr);
-			BUG();
+			ret = -1;
 			break;
 
 		case PGD_TYPE_SECTION:
-				printk("Removing section mapping for 0x%lx",
-				       vaddr);
-				pgd->entry[pgd_i] = 0;
-				pgd->entry[pgd_i] |= PGD_TYPE_FAULT;
+			printk("Removing section mapping for 0x%lx",
+			       vaddr);
+			pgd->entry[pgd_i] = 0;
+			pgd->entry[pgd_i] |= PGD_TYPE_FAULT;
+			ret = 0;
 			break;
 
 		case PGD_TYPE_FINE:
@@ -352,11 +358,13 @@ void remove_mapping_pgd(unsigned long vaddr, pgd_table_t *pgd)
 	/* The tlb must be invalidated here because it might have cached the
 	 * old translation for this mapping. */
 	arm_invalidate_tlb();
+
+	return ret;
 }
 
-void remove_mapping(unsigned long vaddr)
+int remove_mapping(unsigned long vaddr)
 {
-	remove_mapping_pgd(vaddr, current->pgd);
+	return remove_mapping_pgd(vaddr, current->pgd);
 }
 
 /*
diff --git a/tasks/mm0/include/mmap.h b/tasks/mm0/include/mmap.h
index b8695d0..af663d1 100644
--- a/tasks/mm0/include/mmap.h
+++ b/tasks/mm0/include/mmap.h
@@ -24,7 +24,7 @@
 struct vm_area *vma_new(unsigned long pfn_start, unsigned long npages,
 			unsigned int flags, unsigned long file_offset);
 
-int do_munmap(struct tcb *task, void *vaddr, unsigned long size);
+int do_munmap(struct tcb *task, unsigned long vaddr, unsigned long size);
 
 void *do_mmap(struct vm_file *mapfile, unsigned long f_offset, struct tcb *t,
 	      unsigned long map_address, unsigned int flags, unsigned int pages);
diff --git a/tasks/mm0/src/mmap.c b/tasks/mm0/src/mmap.c
index 7bd2ac1..aee0380 100644
--- a/tasks/mm0/src/mmap.c
+++ b/tasks/mm0/src/mmap.c
@@ -146,10 +146,9 @@ void *do_mmap(struct vm_file *mapfile, unsigned long file_offset,
 	      struct tcb *task, unsigned long map_address,
 	      unsigned int flags, unsigned int npages)
 {
-	unsigned long map_pfn = __pfn(map_address);
-	unsigned long file_npages;
-	struct vm_area *new, *mapped;
 	struct vm_obj_link *vmo_link, *vmo_link2;
+	unsigned long file_npages;
+	struct vm_area *new;
 	int err;
 
 	/* Set up devzero if none given */
diff --git a/tasks/mm0/src/munmap.c b/tasks/mm0/src/munmap.c
index 5f22a3c..18b97cb 100644
--- a/tasks/mm0/src/munmap.c
+++ b/tasks/mm0/src/munmap.c
@@ -9,12 +9,14 @@
 #include <l4/lib/math.h>
 #include <l4lib/arch/syslib.h>
 #include <vm_area.h>
+#include <lib/malloc.h>
 
 /* This splits a vma, splitter region must be in the *middle* of original vma */
 int vma_split(struct vm_area *vma, struct tcb *task,
 	      const unsigned long pfn_start, const unsigned long pfn_end)
 {
 	struct vm_area *new;
+	unsigned long unmap_start = pfn_start, unmap_end = pfn_end;
 
 	/* Allocate an uninitialised vma first */
 	if (!(new = vma_new(0, 0, 0, 0)))
@@ -43,6 +45,10 @@ int vma_split(struct vm_area *vma, struct tcb *task,
 	/* Add new one next to original vma */
 	list_add_tail(&new->list, &vma->list);
 
+	/* Unmap the removed portion */
+	BUG_ON(l4_unmap((void *)__pfn_to_addr(unmap_start),
+	       unmap_end - unmap_start, task->tid) < 0);
+
 	return 0;
 }
 
@@ -50,20 +56,49 @@ int vma_split(struct vm_area *vma, struct tcb *task,
 int vma_shrink(struct vm_area *vma, struct tcb *task,
 	       const unsigned long pfn_start, const unsigned long pfn_end)
 {
-	unsigned long diff;
+	unsigned long diff, unmap_start, unmap_end;
 
 	/* Shrink from the end */
 	if (vma->pfn_start < pfn_start) {
 		BUG_ON(pfn_start >= vma->pfn_end);
+		unmap_start = pfn_start;
+		unmap_end = vma->pfn_end;
 		vma->pfn_end = pfn_start;
 
 	/* Shrink from the beginning */
 	} else if (vma->pfn_end > pfn_end) {
 		BUG_ON(pfn_end <= vma->pfn_start);
+		unmap_start = vma->pfn_start;
+		unmap_end = pfn_end;
 		diff = pfn_end - vma->pfn_start;
 		vma->file_offset += diff;
 		vma->pfn_start = pfn_end;
-	} else BUG();
+	} else
+		BUG();
+
+	/* Unmap the shrinked portion */
+	BUG_ON(l4_unmap((void *)__pfn_to_addr(unmap_start),
+	       unmap_end - unmap_start, task->tid) < 0);
+
+	return 0;
+}
+
+/* Destroys a single vma from a task and unmaps its range from task space */
+int vma_destroy_single(struct tcb *task, struct vm_area *vma)
+{
+	int ret;
+
+	/* Release all object links */
+	if ((ret = vma_drop_merge_delete_all(vma)) < 0)
+		return ret;
+
+	/* Unmap the whole vma address range */
+	BUG_ON(l4_unmap((void *)__pfn_to_addr(vma->pfn_start),
+	       vma->pfn_end - vma->pfn_start, task->tid) < 0);
+
+	/* Unlink and delete vma */
+	list_del(&vma->list);
+	kfree(vma);
 
 	return 0;
 }
@@ -84,7 +119,7 @@ int vma_unmap(struct vm_area *vma, struct tcb *task,
 		return vma_shrink(vma, task, pfn_start, pfn_end);
 	/* Destroy needed? */
 	else if ((vma->pfn_start >= pfn_start) && (vma->pfn_end <= pfn_end))
-		return vma_drop_merge_delete_all(vma);
+		return vma_destroy_single(task, vma);
 	else
 		BUG();
 
@@ -158,9 +193,6 @@ int do_munmap(struct tcb *task, unsigned long vaddr, unsigned long npages)
 		}
 	}
 
-	/* Unmap those pages from the task address space */
-	l4_unmap(vaddr, npages, task->tid);
-
 	return 0;
 }
 
diff --git a/tasks/mm0/src/shm.c b/tasks/mm0/src/shm.c
index 1ec2b0a..1f05550 100644
--- a/tasks/mm0/src/shm.c
+++ b/tasks/mm0/src/shm.c
@@ -146,7 +146,7 @@ int do_shmdt(struct tcb *task, struct vm_file *shm)
 	int err;
 
 	if ((err = do_munmap(task,
-			     shm_file_to_desc(shm)->shm_addr,
+			     (unsigned long)shm_file_to_desc(shm)->shm_addr,
 			     shm_file_to_desc(shm)->npages)) < 0)
 		return err;