diff --git a/lib/preprocessor.js b/lib/preprocessor.js
index 54f6075..db988c8 100644
--- a/lib/preprocessor.js
+++ b/lib/preprocessor.js
@@ -125,6 +125,9 @@ function createCoveragePreprocessor (logger, helper, basePath, reporters, covera
       sourceCache[jsPath] = content
 
       if (includeAllSources) {
+        // reset stateful regex
+        coverageObjRegex.lastIndex = 0
+
         var coverageObjMatch = coverageObjRegex.exec(instrumentedCode)
 
         if (coverageObjMatch !== null) {