diff --git a/support.js b/support.js
index effc2cdb..efa5a9d7 100644
--- a/support.js
+++ b/support.js
@@ -15,7 +15,7 @@ afterEach(() => {
     const applicationSourceCoverage = win.__coverage__
 
     if (applicationSourceCoverage) {
-      cy.task('combineCoverage', applicationSourceCoverage)
+      cy.task('combineCoverage', JSON.stringify(applicationSourceCoverage))
     }
   })
 })
@@ -46,7 +46,7 @@ after(() => {
           // original failed request
           return
         }
-        cy.task('combineCoverage', coverage)
+        cy.task('combineCoverage', JSON.stringify(coverage))
       })
   }
 
@@ -67,7 +67,7 @@ after(() => {
       (fileCoverage, filename) =>
         filename.startsWith(specFolder) || filename.startsWith(supportFolder)
     )
-    cy.task('combineCoverage', coverage)
+    cy.task('combineCoverage', JSON.stringify(coverage))
   }
 
   // when all tests finish, lets generate the coverage report
diff --git a/task.js b/task.js
index bb7a9e20..6965f0f2 100644
--- a/task.js
+++ b/task.js
@@ -61,7 +61,8 @@ module.exports = {
    * Combines coverage information from single test
    * with previously collected coverage.
    */
-  combineCoverage (coverage) {
+  combineCoverage (coverageString) {
+    const coverage = JSON.parse(coverageString)
     fixSourcePathes(coverage)
     const previous = existsSync(nycFilename)
       ? JSON.parse(readFileSync(nycFilename))