diff --git a/kernel/src/sys/mem.cpp b/kernel/src/sys/mem.cpp
index abd27aef..d0744b74 100644
--- a/kernel/src/sys/mem.cpp
+++ b/kernel/src/sys/mem.cpp
@@ -14,7 +14,13 @@ void sys_mmap(Context* context, void* address, size_t size, int flags)
 {
     if (size < PAGE_SIZE)
     {
-        kdbgln("sys_mmap: size too small");
+        kwarnln("mmap(): size too small");
+        context->rax = MAP_FAIL(EINVAL);
+        return;
+    }
+    if (size % PAGE_SIZE)
+    {
+        kwarnln("mmap(): size not a multiple of PAGE_SIZE");
         context->rax = MAP_FAIL(EINVAL);
         return;
     }
@@ -22,11 +28,11 @@ void sys_mmap(Context* context, void* address, size_t size, int flags)
     if (flags & MAP_READ_WRITE) real_flags |= MAP_READ_WRITE;
     if (address)
     {
-        kdbgln("sys_mmap: %ld pages at address %p, %s", size / PAGE_SIZE, address,
+        kdbgln("mmap(): %ld pages at address %p, %s", size / PAGE_SIZE, address,
                real_flags & MAP_READ_WRITE ? "rw" : "ro");
         if (VMM::get_physical((uint64_t)address) != (uint64_t)-1) // Address is already used.
         {
-            kdbgln("attempt to mmap an already mapped address");
+            kwarnln("attempt to map an already mapped address");
             context->rax = MAP_FAIL(ENOMEM);
             return;
         }
@@ -35,29 +41,29 @@ void sys_mmap(Context* context, void* address, size_t size, int flags)
                                                    Utilities::get_blocks_from_size(PAGE_SIZE, size), real_flags);
         if (result)
         {
-            kdbgln("mmap succeeded: %p", result);
+            kdbgln("mmap() succeeded: %p", result);
             context->rax = (uint64_t)result;
             return;
         }
         else
         {
-            kdbgln("mmap failed");
+            kwarnln("mmap() failed");
             context->rax = MAP_FAIL(ENOMEM);
             return;
         }
     }
-    kdbgln("sys_mmap: %ld pages at any address, %s", Utilities::get_blocks_from_size(PAGE_SIZE, size),
+    kdbgln("mmap(): %ld pages at any address, %s", Utilities::get_blocks_from_size(PAGE_SIZE, size),
            real_flags & MAP_READ_WRITE ? "rw" : "ro");
     void* result = MemoryManager::get_pages(Utilities::get_blocks_from_size(PAGE_SIZE, size), real_flags);
     if (result)
     {
-        kdbgln("mmap succeeded: %p", result);
+        kdbgln("mmap() succeeded: %p", result);
         context->rax = (uint64_t)result;
         return;
     }
     else
     {
-        kdbgln("mmap failed");
+        kwarnln("mmap() failed");
         context->rax = MAP_FAIL(ENOMEM);
         return;
     }
@@ -65,29 +71,35 @@ void sys_mmap(Context* context, void* address, size_t size, int flags)
 
 void sys_munmap(Context* context, void* address, size_t size)
 {
-    kdbgln("sys_munmap: attempting to unmap %p", address);
+    kdbgln("munmap(): attempting to unmap %p", address);
     if (size < PAGE_SIZE)
     {
-        kdbgln("munmap failed: size is too small");
+        kwarnln("munmap() failed: size is too small");
+        context->rax = -EINVAL;
+        return;
+    }
+    if (size % PAGE_SIZE)
+    {
+        kwarnln("munmap() failed: size is not a multiple of PAGE_SIZE");
         context->rax = -EINVAL;
         return;
     }
     if (!address)
     {
-        kdbgln("munmap failed: attempted to unmap page 0");
+        kwarnln("munmap() failed: attempted to unmap page 0");
         context->rax = -EINVAL;
         return;
     }
     uint64_t flags = VMM::get_flags((uint64_t)address);
     if (!(flags & MAP_USER))
     {
-        kdbgln("munmap failed: attempted to unmap a kernel page");
+        kwarnln("munmap() failed: attempted to unmap a non-existent or kernel page");
         context->rax = -EINVAL;
         return;
     }
     uint64_t offset = (uint64_t)address % PAGE_SIZE;
     MemoryManager::release_pages((void*)((uint64_t)address - offset), Utilities::get_blocks_from_size(PAGE_SIZE, size));
-    kdbgln("munmap succeeded");
+    kdbgln("munmap() succeeded");
     context->rax = 0;
     return;
 }
\ No newline at end of file