diff --git a/package.json b/package.json
index 19235a829..6818080ff 100644
--- a/package.json
+++ b/package.json
@@ -62,7 +62,7 @@
   "devDependencies": {
     "chai": "^3.0.0",
     "sinon": "^1.15.3",
-    "source-map-fixtures": "^0.1.0",
+    "source-map-fixtures": "^0.2.0",
     "standard": "^5.2.1",
     "tap": "^1.3.4"
   },
diff --git a/test/fixtures/_generateCoverage.js b/test/fixtures/_generateCoverage.js
index b154169b4..d9ef349e4 100644
--- a/test/fixtures/_generateCoverage.js
+++ b/test/fixtures/_generateCoverage.js
@@ -8,20 +8,20 @@ var path = require('path')
 
 var _ = require('lodash')
 var rimraf = require('rimraf')
+var sourceMapFixtures = require('source-map-fixtures')
 
 var NYC = require('../../')
 
-// Load the 'branching' source map fixture.
-var fixture = require('source-map-fixtures').inline('branching')
-
-// Prevent pollution from earlier nyc runs.
-var tempDirectory = path.join(__dirname, '.nyc_output')
-rimraf.sync(tempDirectory)
+// Load source map fixtures.
+var fixtures = {
+  bundle: sourceMapFixtures.inline('bundle'),
+  inline: sourceMapFixtures.inline('branching'),
+  none: sourceMapFixtures.none('branching')
+}
 
 // Inject nyc into this process.
 var nyc = (new NYC({
-  cwd: path.join(__dirname, '..', '..'),
-  tempDirectory: tempDirectory
+  cwd: path.join(__dirname, '..', '..')
 })).wrap()
 // Override the exclude option, source-map-fixtures is inside node_modules but
 // should not be excluded when generating the coverage report.
@@ -29,20 +29,31 @@ nyc.exclude = []
 
 // Require the fixture so nyc can instrument it, then run it so there's code
 // coverage.
-fixture.require().run()
-
-// Write the coverage file so reports can be loaded.
-nyc.writeCoverageFile()
+fixtures.bundle.require().branching()
+fixtures.inline.require().run()
+fixtures.none.require().run()
+
+// Copy NYC#writeCoverageFile() behavior to get the coverage object, before
+// source maps have been applied.
+var coverage = global.__coverage__
+if (typeof __coverage__ === 'object') coverage = __coverage__
+if (!coverage) {
+  console.error('No coverage.')
+  process.exit(1)
+}
 
-var reports = _.values(nyc._loadReports()[0])
-if (reports.length !== 1) {
-  console.error('Expected 1 report to be generated, got ' + reports.length)
+var reports = _.values(coverage)
+if (reports.length !== 3) {
+  console.error('Expected 3 reports to be generated, got ' + reports.length)
   process.exit(1)
 }
 
-var coverage = reports[0]
-fs.writeFileSync(
-  path.join(__dirname, 'coverage.js'),
-  '// Generated using node test/fixtures/_generateCoverage.js\n' +
-  'exports[' + JSON.stringify(coverage.path) + '] = ' + JSON.stringify(coverage, null, 2) + '\n')
-console.log('Written coverage report.')
+var out = fs.createWriteStream(path.join(__dirname, 'coverage.js'))
+out.write('// Generated using node test/fixtures/_generateCoverage.js\n')
+reports.forEach(function (coverage) {
+  out.write('exports[' + JSON.stringify(coverage.path) + '] = ' + JSON.stringify(coverage, null, 2) + '\n')
+})
+out.end()
+out.on('finish', function () {
+  console.log('Written coverage report.')
+})
diff --git a/test/fixtures/coverage.js b/test/fixtures/coverage.js
index c8f8ab9ad..d2d653feb 100644
--- a/test/fixtures/coverage.js
+++ b/test/fixtures/coverage.js
@@ -1,4 +1,215 @@
 // Generated using node test/fixtures/_generateCoverage.js
+exports["./node_modules/source-map-fixtures/fixtures/bundle-inline.js"] = {
+  "path": "./node_modules/source-map-fixtures/fixtures/bundle-inline.js",
+  "s": {
+    "1": 1,
+    "2": 1,
+    "3": 0,
+    "4": 1,
+    "5": 0,
+    "6": 1,
+    "7": 1,
+    "8": 0,
+    "9": 1,
+    "10": 1,
+    "11": 1
+  },
+  "b": {
+    "1": [
+      0,
+      1
+    ]
+  },
+  "f": {
+    "1": 0,
+    "2": 0,
+    "3": 1
+  },
+  "fnMap": {
+    "1": {
+      "name": "(anonymous_1)",
+      "line": 6,
+      "loc": {
+        "start": {
+          "line": 6,
+          "column": 8
+        },
+        "end": {
+          "line": 6,
+          "column": 20
+        }
+      }
+    },
+    "2": {
+      "name": "(anonymous_2)",
+      "line": 10,
+      "loc": {
+        "start": {
+          "line": 10,
+          "column": 8
+        },
+        "end": {
+          "line": 10,
+          "column": 20
+        }
+      }
+    },
+    "3": {
+      "name": "(anonymous_3)",
+      "line": 14,
+      "loc": {
+        "start": {
+          "line": 14,
+          "column": 8
+        },
+        "end": {
+          "line": 14,
+          "column": 21
+        }
+      }
+    }
+  },
+  "statementMap": {
+    "1": {
+      "start": {
+        "line": 3,
+        "column": 0
+      },
+      "end": {
+        "line": 5,
+        "column": 3
+      }
+    },
+    "2": {
+      "start": {
+        "line": 6,
+        "column": 0
+      },
+      "end": {
+        "line": 8,
+        "column": 2
+      }
+    },
+    "3": {
+      "start": {
+        "line": 7,
+        "column": 2
+      },
+      "end": {
+        "line": 7,
+        "column": 51
+      }
+    },
+    "4": {
+      "start": {
+        "line": 10,
+        "column": 0
+      },
+      "end": {
+        "line": 12,
+        "column": 2
+      }
+    },
+    "5": {
+      "start": {
+        "line": 11,
+        "column": 2
+      },
+      "end": {
+        "line": 11,
+        "column": 12
+      }
+    },
+    "6": {
+      "start": {
+        "line": 14,
+        "column": 0
+      },
+      "end": {
+        "line": 18,
+        "column": 2
+      }
+    },
+    "7": {
+      "start": {
+        "line": 15,
+        "column": 2
+      },
+      "end": {
+        "line": 17,
+        "column": 3
+      }
+    },
+    "8": {
+      "start": {
+        "line": 16,
+        "column": 4
+      },
+      "end": {
+        "line": 16,
+        "column": 16
+      }
+    },
+    "9": {
+      "start": {
+        "line": 20,
+        "column": 0
+      },
+      "end": {
+        "line": 20,
+        "column": 22
+      }
+    },
+    "10": {
+      "start": {
+        "line": 21,
+        "column": 0
+      },
+      "end": {
+        "line": 21,
+        "column": 19
+      }
+    },
+    "11": {
+      "start": {
+        "line": 22,
+        "column": 0
+      },
+      "end": {
+        "line": 22,
+        "column": 19
+      }
+    }
+  },
+  "branchMap": {
+    "1": {
+      "line": 15,
+      "type": "if",
+      "locations": [
+        {
+          "start": {
+            "line": 15,
+            "column": 2
+          },
+          "end": {
+            "line": 15,
+            "column": 2
+          }
+        },
+        {
+          "start": {
+            "line": 15,
+            "column": 2
+          },
+          "end": {
+            "line": 15,
+            "column": 2
+          }
+        }
+      ]
+    }
+  }
+}
 exports["./node_modules/source-map-fixtures/fixtures/branching-inline.js"] = {
   "path": "./node_modules/source-map-fixtures/fixtures/branching-inline.js",
   "s": {
@@ -114,3 +325,118 @@ exports["./node_modules/source-map-fixtures/fixtures/branching-inline.js"] = {
     }
   }
 }
+exports["./node_modules/source-map-fixtures/fixtures/branching-none.js"] = {
+  "path": "./node_modules/source-map-fixtures/fixtures/branching-none.js",
+  "s": {
+    "1": 1,
+    "2": 1,
+    "3": 1,
+    "4": 0,
+    "5": 1
+  },
+  "b": {
+    "1": [
+      0,
+      1
+    ]
+  },
+  "f": {
+    "1": 1
+  },
+  "fnMap": {
+    "1": {
+      "name": "(anonymous_1)",
+      "line": 6,
+      "loc": {
+        "start": {
+          "line": 6,
+          "column": 8
+        },
+        "end": {
+          "line": 6,
+          "column": 21
+        }
+      }
+    }
+  },
+  "statementMap": {
+    "1": {
+      "start": {
+        "line": 3,
+        "column": 0
+      },
+      "end": {
+        "line": 5,
+        "column": 3
+      }
+    },
+    "2": {
+      "start": {
+        "line": 6,
+        "column": 0
+      },
+      "end": {
+        "line": 10,
+        "column": 2
+      }
+    },
+    "3": {
+      "start": {
+        "line": 7,
+        "column": 2
+      },
+      "end": {
+        "line": 9,
+        "column": 3
+      }
+    },
+    "4": {
+      "start": {
+        "line": 8,
+        "column": 4
+      },
+      "end": {
+        "line": 8,
+        "column": 16
+      }
+    },
+    "5": {
+      "start": {
+        "line": 11,
+        "column": 0
+      },
+      "end": {
+        "line": 11,
+        "column": 16
+      }
+    }
+  },
+  "branchMap": {
+    "1": {
+      "line": 7,
+      "type": "if",
+      "locations": [
+        {
+          "start": {
+            "line": 7,
+            "column": 2
+          },
+          "end": {
+            "line": 7,
+            "column": 2
+          }
+        },
+        {
+          "start": {
+            "line": 7,
+            "column": 2
+          },
+          "end": {
+            "line": 7,
+            "column": 2
+          }
+        }
+      ]
+    }
+  }
+}
diff --git a/test/source-map-cache.js b/test/source-map-cache.js
index 7e63feb35..5bfc96b46 100644
--- a/test/source-map-cache.js
+++ b/test/source-map-cache.js
@@ -3,80 +3,111 @@
 var _ = require('lodash')
 var path = require('path')
 
-var fixture = require('source-map-fixtures').inline('branching')
-// Coverage for the fixture is stored relative to the root directory. Here
-// compute the path to the fixture file relative to the root directory.
-var relpath = './' + path.relative(path.join(__dirname, '..'), fixture.file)
-// the sourcemap itself remaps the path.
-var mappedPath = './' + path.join(path.dirname(relpath), '../src/branching.js')
-// Compute the number of lines in the original source, excluding any line break
-// at the end of the file.
-var maxLine = fixture.sourceContentSync().trimRight().split(/\r?\n/).length
+var sourceMapFixtures = require('source-map-fixtures')
+
+// Load source map fixtures.
+var covered = _.mapValues({
+  bundle: sourceMapFixtures.inline('bundle'),
+  inline: sourceMapFixtures.inline('branching'),
+  none: sourceMapFixtures.none('branching')
+}, function (fixture) {
+  return _.assign({
+    // Coverage for the fixture is stored relative to the root directory. Here
+    // compute the path to the fixture file relative to the root directory.
+    relpath: './' + path.relative(path.join(__dirname, '..'), fixture.file),
+    // the sourcemap itself remaps the path.
+    mappedPath: './' + path.relative(path.join(__dirname, '..'), fixture.sourceFile),
+    // Compute the number of lines in the original source, excluding any line
+    // break at the end of the file.
+    maxLine: fixture.sourceContentSync().trimRight().split(/\r?\n/).length
+  }, fixture)
+})
 
 var SourceMapCache = require('../lib/source-map-cache')
 var sourceMapCache = new SourceMapCache()
-sourceMapCache.add(relpath, fixture.contentSync())
+_.forOwn(covered, function (fixture) {
+  sourceMapCache.add(fixture.relpath, fixture.contentSync())
+})
 
 var coverage = require('./fixtures/coverage')
+var fixture = covered.inline
 
 require('chai').should()
 require('tap').mochaGlobals()
 
 describe('source-map-cache', function () {
+  it('does not rewrite if there is no source map', function () {
+    var mappedCoverage = sourceMapCache.applySourceMaps(coverage)
+    mappedCoverage[covered.none.relpath].should.eql(coverage[covered.none.relpath])
+  })
+
+  describe('path', function () {
+    it('does not rewrite path if the source map has more than one source', function () {
+      var mappedCoverage = sourceMapCache.applySourceMaps(coverage)
+      mappedCoverage.should.have.property(covered.bundle.relpath)
+      mappedCoverage[covered.bundle.relpath].should.not.eql(coverage[covered.bundle.relpath])
+    })
+
+    it('rewrites path if the source map exactly one source', function () {
+      var mappedCoverage = sourceMapCache.applySourceMaps(_.pick(coverage, fixture.relpath))
+      mappedCoverage.should.have.property(fixture.mappedPath)
+    })
+  })
+
   describe('statements', function () {
     it('drops statements that have no mapping back to the original source code', function () {
       var mappedCoverage = sourceMapCache.applySourceMaps(coverage)
-      Object.keys(mappedCoverage[mappedPath].s)
-        .should.be.lt(coverage[relpath].s)
-      Object.keys(mappedCoverage[mappedPath].statementMap).length
-        .should.equal(Object.keys(mappedCoverage[mappedPath].s).length)
+      Object.keys(mappedCoverage[fixture.mappedPath].s)
+        .should.be.lt(coverage[fixture.relpath].s)
+      Object.keys(mappedCoverage[fixture.mappedPath].statementMap).length
+        .should.equal(Object.keys(mappedCoverage[fixture.mappedPath].s).length)
     })
 
     it('maps all statements back to their original loc', function () {
       var mappedCoverage = sourceMapCache.applySourceMaps(coverage)
-      var statements = _.values(mappedCoverage[mappedPath].statementMap)
+      var statements = _.values(mappedCoverage[fixture.mappedPath].statementMap)
       var maxStatement = _.max(statements, function (s) {
         return Math.max(s.start.line, s.end.line)
       })
-      Math.max(maxStatement.start.line, maxStatement.end.line).should.be.lte(maxLine)
+      Math.max(maxStatement.start.line, maxStatement.end.line).should.be.lte(fixture.maxLine)
     })
   })
 
   describe('functions', function () {
     it('drops functions that have no mapping back to the original source code', function () {
       var mappedCoverage = sourceMapCache.applySourceMaps(coverage)
-      Object.keys(mappedCoverage[mappedPath].f)
-        .should.be.lt(coverage[relpath].f)
-      Object.keys(mappedCoverage[mappedPath].fnMap).length
-        .should.equal(Object.keys(mappedCoverage[mappedPath].f).length)
+      Object.keys(mappedCoverage[fixture.mappedPath].f)
+        .should.be.lt(coverage[fixture.relpath].f)
+      Object.keys(mappedCoverage[fixture.mappedPath].fnMap).length
+        .should.equal(Object.keys(mappedCoverage[fixture.mappedPath].f).length)
     })
 
     it('maps all functions back to their original loc', function () {
       var mappedCoverage = sourceMapCache.applySourceMaps(coverage)
-      var functions = _.values(mappedCoverage[mappedPath].fnMap)
+      var functions = _.values(mappedCoverage[fixture.mappedPath].fnMap)
       var maxFunction = _.max(functions, function (f) {
         return f.line
       })
-      Math.max(maxFunction.line).should.be.lte(maxLine)
+      Math.max(maxFunction.line).should.be.lte(fixture.maxLine)
     })
   })
 
   describe('branches', function () {
     it('drops branches that have no mapping back to the original source code', function () {
       var mappedCoverage = sourceMapCache.applySourceMaps(coverage)
-      Object.keys(mappedCoverage[mappedPath].b)
-        .should.be.lt(coverage[relpath].b)
-      Object.keys(mappedCoverage[mappedPath].branchMap).length
-        .should.equal(Object.keys(mappedCoverage[mappedPath].b).length)
+      Object.keys(mappedCoverage[fixture.mappedPath].b)
+        .should.be.lt(coverage[fixture.relpath].b)
+      Object.keys(mappedCoverage[fixture.mappedPath].branchMap).length
+        .should.equal(Object.keys(mappedCoverage[fixture.mappedPath].b).length)
     })
 
     it('maps all branches back to their original loc', function () {
       var mappedCoverage = sourceMapCache.applySourceMaps(coverage)
-      var branches = _.values(mappedCoverage[mappedPath].branchMap)
+      var branches = _.values(mappedCoverage[fixture.mappedPath].branchMap)
       var maxBranch = _.max(branches, function (b) {
         return b.line
       })
-      Math.max(maxBranch.line).should.be.lte(maxLine)
+      Math.max(maxBranch.line).should.be.lte(fixture.maxLine)
     })
   })
 })