diff --git a/renderdoc/driver/vulkan/wrappers/vk_resource_funcs.cpp b/renderdoc/driver/vulkan/wrappers/vk_resource_funcs.cpp
index ec794bc5d..e68dff5d5 100644
--- a/renderdoc/driver/vulkan/wrappers/vk_resource_funcs.cpp
+++ b/renderdoc/driver/vulkan/wrappers/vk_resource_funcs.cpp
@@ -869,12 +869,16 @@ bool WrappedVulkan::Serialise_vkFlushMappedMemoryRanges(SerialiserType &ser, VkD
     if(!state->refData)
     {
       // if we're in this case, the range should be for the whole memory region.
-      RDCASSERT(MemRange.offset == state->mapOffset && memRangeSize == state->mapSize);
+      RDCASSERT(MemRange.offset == state->mapOffset && memRangeSize == state->mapSize,
+                MemRange.offset, memRangeSize, state->mapOffset, state->mapSize);
 
       // allocate ref data so we can compare next time to minimise serialised data
       state->refData = AllocAlignedBuffer((size_t)state->mapSize);
     }
 
+    // the memory range offset should always be at least the map offset
+    RDCASSERT(MemRange.offset >= state->mapOffset, MemRange.offset, state->mapOffset);
+
     // it's no longer safe to use state->mappedPtr, we need to save *precisely* what
     // was serialised. We do this by copying out of the serialiser since we know this
     // memory is not changing
@@ -882,7 +886,7 @@ bool WrappedVulkan::Serialise_vkFlushMappedMemoryRanges(SerialiserType &ser, VkD
 
     const byte *serialisedData = ser.GetWriter()->GetData() + offs;
 
-    memcpy(state->refData, serialisedData, (size_t)memRangeSize);
+    memcpy(state->refData + MemRange.offset - state->mapOffset, serialisedData, (size_t)memRangeSize);
   }
 
   return true;
diff --git a/util/test/demos/vk/vk_misaligned_dirty.cpp b/util/test/demos/vk/vk_misaligned_dirty.cpp
index 43a34bbbd..29abc9039 100644
--- a/util/test/demos/vk/vk_misaligned_dirty.cpp
+++ b/util/test/demos/vk/vk_misaligned_dirty.cpp
@@ -95,8 +95,8 @@ RD_TEST(VK_Misaligned_Dirty, VulkanGraphicsTest)
     float counter = 0;
     while(Running())
     {
-      mapped[2] = counter;
       counter += 1.0f;
+      mapped[2] = counter;
 
       VkCommandBuffer cmd = GetCommandBuffer();
 
@@ -106,10 +106,10 @@ RD_TEST(VK_Misaligned_Dirty, VulkanGraphicsTest)
       setMarker(cmd, "First Submit");
       vkCmdUpdateBuffer(cmd, copy_src.buffer, sizeof(Vec3f), sizeof(Vec4f), &tri[0].col);
       vkEndCommandBuffer(cmd);
-      Submit(0, 2, {cmd});
+      Submit(0, 3, {cmd});
 
-      mapped[2] = counter;
       counter += 1.0f;
+      mapped[2] = counter;
 
       cmd = GetCommandBuffer();
 
@@ -149,7 +149,19 @@ RD_TEST(VK_Misaligned_Dirty, VulkanGraphicsTest)
 
       vkEndCommandBuffer(cmd);
 
-      Submit(1, 2, {cmd});
+      Submit(1, 3, {cmd});
+
+      mapped[2] = counter - 1.0f;
+
+      cmd = GetCommandBuffer();
+
+      // create a dummy submit which uses the memory. This will serialise the whole memory contents
+      // (we don't create reference data until after this)
+      vkBeginCommandBuffer(cmd, vkh::CommandBufferBeginInfo());
+      setMarker(cmd, "Third Submit");
+      vkCmdUpdateBuffer(cmd, copy_src.buffer, sizeof(Vec3f), sizeof(Vec4f), &tri[0].col);
+      vkEndCommandBuffer(cmd);
+      Submit(2, 3, {cmd});
 
       Present();
     }
diff --git a/util/test/tests/Vulkan/VK_Misaligned_Dirty.py b/util/test/tests/Vulkan/VK_Misaligned_Dirty.py
index 58c6773d6..c3c8900d4 100644
--- a/util/test/tests/Vulkan/VK_Misaligned_Dirty.py
+++ b/util/test/tests/Vulkan/VK_Misaligned_Dirty.py
@@ -78,9 +78,11 @@ class VK_Misaligned_Dirty(rdtest.TestCase):
 
         checkpoint1 = self.find_draw("First Submit")
         checkpoint2 = self.find_draw("Second Submit")
+        checkpoint3 = self.find_draw("Third Submit")
 
         self.check(checkpoint1 is not None)
         self.check(checkpoint2 is not None)
+        self.check(checkpoint3 is not None)
 
         resources = self.controller.GetResources()
 
@@ -99,13 +101,18 @@ class VK_Misaligned_Dirty(rdtest.TestCase):
         self.controller.SetFrameEvent(checkpoint1.eventId, False)
 
         val = struct.unpack('f', self.controller.GetBufferData(copy_src, 116, 4))
-        self.check(val[0] == 10.0)
+        self.check(val[0] == 11.0)
 
         self.controller.SetFrameEvent(checkpoint2.eventId, False)
 
         val = struct.unpack('f', self.controller.GetBufferData(copy_src, 116, 4))
-        self.check(val[0] == 11.0)
+        self.check(val[0] == 12.0)
         val = struct.unpack('f', self.controller.GetBufferData(vb, 116, 4))
+        self.check(val[0] == 12.0)
+
+        self.controller.SetFrameEvent(checkpoint3.eventId, False)
+
+        val = struct.unpack('f', self.controller.GetBufferData(copy_src, 116, 4))
         self.check(val[0] == 11.0)
 
         rdtest.log.success("buffers have correct values in both submits")