diff --git a/lib/source-map-consumer.js b/lib/source-map-consumer.js
index 17ef92b1..9c200252 100644
--- a/lib/source-map-consumer.js
+++ b/lib/source-map-consumer.js
@@ -918,6 +918,8 @@ class IndexedSourceMapConsumer extends SourceMapConsumer {
         }
       }
 
+      generatedPosition.line += lineShift;
+
       if (
         generatedPosition.lastColumn === Infinity &&
         nextSection &&
@@ -926,7 +928,6 @@ class IndexedSourceMapConsumer extends SourceMapConsumer {
         generatedPosition.lastColumn =
           nextSection.generatedOffset.generatedColumn - 2;
       }
-      generatedPosition.line += lineShift;
 
       return generatedPosition;
     }
@@ -961,6 +962,8 @@ class IndexedSourceMapConsumer extends SourceMapConsumer {
           }
         }
 
+        generatedPosition.line += lineShift;
+
         if (
           generatedPosition.lastColumn === Infinity &&
           nextSection &&
@@ -969,7 +972,6 @@ class IndexedSourceMapConsumer extends SourceMapConsumer {
           generatedPosition.lastColumn =
             nextSection.generatedOffset.generatedColumn - 2;
         }
-        generatedPosition.line += lineShift;
 
         return generatedPosition;
       });
@@ -994,6 +996,8 @@ class IndexedSourceMapConsumer extends SourceMapConsumer {
             }
           }
 
+          mapping.generatedLine += lineShift;
+
           if (
             mapping.lastGeneratedColumn === Infinity &&
             nextSection &&
@@ -1002,7 +1006,6 @@ class IndexedSourceMapConsumer extends SourceMapConsumer {
             mapping.lastGeneratedColumn =
               nextSection.generatedOffset.generatedColumn - 2;
           }
-          mapping.generatedLine += lineShift;
 
           aCallback.call(this, mapping);
         },
diff --git a/test/test-source-map-consumer.js b/test/test-source-map-consumer.js
index 8cf50988..af73cab5 100644
--- a/test/test-source-map-consumer.js
+++ b/test/test-source-map-consumer.js
@@ -2192,3 +2192,41 @@ exports["test a mapping at the boundary of indexed source map offset"] =
     util.assertMapping(1, 0, "/the/root/one.js", 1, 0, null, null, map, assert);
     map.destroy();
   };
+
+exports[
+  "test computeColumnSpans with an indexed map whose sections do not start on line 1"
+] = async function (assert) {
+  const section = source => ({
+    version: 3,
+    sources: [source],
+    names: [],
+    mappings: "AAAA",
+  });
+  const map = await new SourceMapConsumer({
+    version: 3,
+    sections: [
+      { offset: { line: 0, column: 0 }, map: section("a.js") },
+      { offset: { line: 2, column: 0 }, map: section("b.js") },
+      { offset: { line: 2, column: 10 }, map: section("c.js") },
+    ],
+  });
+  map.computeColumnSpans();
+
+  // "b.js" ends where "c.js" begins on generated line 3.
+  assert.deepEqual(
+    map.generatedPositionFor({ source: "b.js", line: 1, column: 0 }),
+    { line: 3, column: 0, lastColumn: 9 }
+  );
+  assert.deepEqual(map.allGeneratedPositionsFor({ source: "b.js", line: 1 }), [
+    { line: 3, column: 0, lastColumn: 9 },
+  ]);
+
+  const lastColumns = {};
+  map.eachMapping(m => {
+    lastColumns[m.source] = m.lastGeneratedColumn;
+  });
+  assert.equal(lastColumns["b.js"], 9);
+  assert.equal(lastColumns["c.js"], Infinity);
+
+  map.destroy();
+};