diff --git a/groupmesh.cpp b/groupmesh.cpp
index 25306d47..2bffa93e 100644
--- a/groupmesh.cpp
+++ b/groupmesh.cpp
@@ -168,7 +168,9 @@ void Group::GenerateShellAndMesh(void) {
 
             GenerateForStepAndRepeat<SShell>
                 (prev, toStep, &runningShell, src->meshCombine);
-            runningShell.MergeCoincidentSurfaces();
+            if(meshCombine != COMBINE_AS_ASSEMBLE) {
+                runningShell.MergeCoincidentSurfaces();
+            }
         } else {
             SMesh prevm, stepm;
             ZERO(&prevm);
@@ -288,7 +290,9 @@ void Group::GenerateShellAndMesh(void) {
         thisShell.RemapFaces(this, 0);
     }
 
-    thisShell.MergeCoincidentSurfaces();
+    if(meshCombine != COMBINE_AS_ASSEMBLE) {
+        thisShell.MergeCoincidentSurfaces();
+    }
 
     // So now we've got the mesh or shell for this group. Combine it with
     // the previous group's mesh or shell with the requested Boolean, and
@@ -298,7 +302,10 @@ void Group::GenerateShellAndMesh(void) {
     if(pg->runningMesh.IsEmpty() && thisMesh.IsEmpty() && !forceToMesh) {
         SShell *prevs = &(pg->runningShell);
         GenerateForBoolean<SShell>(prevs, &thisShell, &runningShell);
-        runningShell.MergeCoincidentSurfaces();
+
+        if(meshCombine != COMBINE_AS_ASSEMBLE) {
+            runningShell.MergeCoincidentSurfaces();
+        }
 
         // If the Boolean failed, then we should note that in the text screen
         // for this group.
diff --git a/solvespace.cpp b/solvespace.cpp
index 59e2542a..67958e0e 100644
--- a/solvespace.cpp
+++ b/solvespace.cpp
@@ -466,6 +466,10 @@ void SolveSpace::MenuAnalyze(int id) {
                 Error("%d edges interfere with other triangles, bad.",
                     SS.nakedEdges.l.n);
             } else {
+                // MakeCertainEdgesInto also reports "naked" edges, which
+                // will include some types of coincident geometry that are
+                // not errors.
+                SS.nakedEdges.Clear();
                 Message("The assembly does not interfere, good.");
             }
             break;