diff --git a/src/dev.rs b/src/dev.rs
index f89a733b..a2cd62d6 100644
--- a/src/dev.rs
+++ b/src/dev.rs
@@ -382,7 +382,11 @@ impl<F: FieldExt> MockProver<F> {
             let original = self.cs.permutations[perm_index]
                 .get_columns()
                 .iter()
-                .map(|c| self.advice[c.index()].clone())
+                .map(|c| match c.column_type() {
+                    Any::Advice => self.advice[c.index()].clone(),
+                    Any::Fixed => self.fixed[c.index()].clone(),
+                    Any::Instance => self.instance[c.index()].clone(),
+                })
                 .collect::<Vec<_>>();
 
             // Iterate over each column of the permutation
diff --git a/src/dev/graph/layout.rs b/src/dev/graph/layout.rs
index 58832534..229c7341 100644
--- a/src/dev/graph/layout.rs
+++ b/src/dev/graph/layout.rs
@@ -187,9 +187,19 @@ impl Layout {
         if let Some(region) = self.current_region {
             let region = &mut self.regions[region];
             region.columns.insert(column);
-            let offset = region.offset.unwrap_or(row);
+
+            // The region offset is the earliest row assigned to.
+            let mut offset = region.offset.unwrap_or(row);
+            if row < offset {
+                // The first row assigned was not at offset 0 within the region.
+                region.rows += offset - row;
+                offset = row;
+            }
+            // The number of rows in this region is the gap between the earliest and
+            // latest rows assigned.
             region.rows = cmp::max(region.rows, row - offset + 1);
             region.offset = Some(offset);
+
             region.cells.push((column, row));
         } else {
             self.loose_cells.push((column, row));