diff --git a/spec/app/row-map-spec.coffee b/spec/app/row-map-spec.coffee
index d1b99fdc8..5442be663 100644
--- a/spec/app/row-map-spec.coffee
+++ b/spec/app/row-map-spec.coffee
@@ -156,3 +156,26 @@ describe "RowMap", ->
         expect(map.bufferRowRangeForScreenRow(11)).toEqual [15, 20]
         expect(map.bufferRowRangeForScreenRow(5)).toEqual [5, 10]
         expect(map.bufferRowRangeForScreenRow(21)).toEqual [25, 30]
+
+  describe ".applyScreenDelta(startScreenRow, delta)", ->
+    describe "when applying a positive delta", ->
+      it "can enlarge the screen side of existing mappings", ->
+        map.mapBufferRowRange(5, 6, 3) # wrapped line
+        map.applyScreenDelta(5, 2) # wrap it twice more
+        expect(map.screenRowRangeForBufferRow(5)).toEqual [5, 10]
+
+    describe "when applying a negative delta", ->
+      it "can collapse the screen side of multiple mappings to 0 until the entire delta has been applied", ->
+        map.mapBufferRowRange(5, 10, 1)  # inner fold 1
+        map.mapBufferRowRange(11, 13, 1)  # inner fold 2
+        map.mapBufferRowRange(15, 20, 1) # inner fold 3
+        map.mapBufferRowRange(22, 27, 1) # following fold
+
+        map.applyScreenDelta(6, -5)
+
+        expect(map.screenRowRangeForBufferRow(5)).toEqual [5, 6]
+        expect(map.screenRowRangeForBufferRow(9)).toEqual [5, 6]
+        expect(map.screenRowRangeForBufferRow(10)).toEqual [6, 6]
+        expect(map.screenRowRangeForBufferRow(19)).toEqual [6, 6]
+        expect(map.screenRowRangeForBufferRow(22)).toEqual [8, 9]
+        expect(map.screenRowRangeForBufferRow(26)).toEqual [8, 9]
diff --git a/src/app/row-map.coffee b/src/app/row-map.coffee
index 4e8fb8267..485f2a6b6 100644
--- a/src/app/row-map.coffee
+++ b/src/app/row-map.coffee
@@ -50,9 +50,18 @@ class RowMap
     { mapping } = @traverseToBufferRow(startBufferRow)
     mapping?.bufferRows += delta
 
-  applyScreenDelta: (startBufferRow, delta) ->
-    { mapping } = @traverseToScreenRow(startBufferRow)
-    mapping?.screenRows += delta
+  applyScreenDelta: (startScreenRow, delta) ->
+    { index } = @traverseToScreenRow(startScreenRow)
+    until delta == 0
+      { bufferRows, screenRows } = @mappings[index]
+      screenRows += delta
+      if screenRows < 0
+        delta = screenRows
+        screenRows = 0
+      else
+        delta = 0
+      @mappings[index] = { bufferRows, screenRows }
+      index++
 
   traverseToBufferRow: (targetBufferRow) ->
     bufferRow = 0