diff --git a/src/main/java/org/micromanager/lightsheetmanager/model/acquisitions/AcquisitionEngine.java b/src/main/java/org/micromanager/lightsheetmanager/model/acquisitions/AcquisitionEngine.java
index dbce269..637ef39 100644
--- a/src/main/java/org/micromanager/lightsheetmanager/model/acquisitions/AcquisitionEngine.java
+++ b/src/main/java/org/micromanager/lightsheetmanager/model/acquisitions/AcquisitionEngine.java
@@ -237,7 +237,10 @@ protected DefaultSummaryMetadata addMMSummaryMetadata(JSONObject summaryMetadata
             }
             summaryMetadata.put(PropertyKey.AXIS_ORDER.key(), axes);
 
-            DefaultSummaryMetadata dsmd = (DefaultSummaryMetadata) dsmb.build();
+            // add "z-step_um" metadata to the image viewer (used in the deskew plugin)
+            DefaultSummaryMetadata dsmd = (DefaultSummaryMetadata) dsmb
+                  .zStepUm(acqSettings_.volumeSettings().sliceStepSize())
+                  .build();
 
             summaryMetadata.put(PropertyKey.MICRO_MANAGER_VERSION.key(),
                   dsmd.getMicroManagerVersion());
diff --git a/src/main/java/org/micromanager/lightsheetmanager/model/acquisitions/AcquisitionEngineSCAPE.java b/src/main/java/org/micromanager/lightsheetmanager/model/acquisitions/AcquisitionEngineSCAPE.java
index 21c85eb..22ab2f1 100644
--- a/src/main/java/org/micromanager/lightsheetmanager/model/acquisitions/AcquisitionEngineSCAPE.java
+++ b/src/main/java/org/micromanager/lightsheetmanager/model/acquisitions/AcquisitionEngineSCAPE.java
@@ -1,6 +1,7 @@
 package org.micromanager.lightsheetmanager.model.acquisitions;
 
 import mmcorej.StrVector;
+import mmcorej.org.json.JSONException;
 import mmcorej.org.json.JSONObject;
 import org.micromanager.MultiStagePosition;
 import org.micromanager.PositionList;
@@ -251,6 +252,11 @@ boolean run() {
         currentAcquisition_ = new Acquisition(sink);
 
         JSONObject summaryMetadata = currentAcquisition_.getSummaryMetadata();
+        try {
+            summaryMetadata.put("z-um_step", acqSettings_.volumeSettings().sliceStepSize());
+        } catch (JSONException e) {
+            studio_.logs().logError("Failed to add z-um_step metadata: " + e.getMessage());
+        }
         DefaultSummaryMetadata dsmd = addMMSummaryMetadata(summaryMetadata, projectionMode);
 
         // TODO(Brandon): where should i get this from?