diff --git a/__tests__/message.test.ts b/__tests__/message.test.ts
index b551fe1..db7ebdc 100644
--- a/__tests__/message.test.ts
+++ b/__tests__/message.test.ts
@@ -16,7 +16,7 @@ describe('buildMessage', () => {
     coverage: [],
     coverageBefore: [],
     coverageFile: 'packages/project_a/coverage/lcov.info'
-  }
+  } as CoveredProject
 
   const projectB = {
     name: 'project_b',
@@ -25,7 +25,7 @@ describe('buildMessage', () => {
     coverage: [],
     coverageBefore: [],
     coverageFile: 'packages/project_b/coverage/lcov.info'
-  }
+  } as CoveredProject
 
   it('returns the correct message when projects array has one project', () => {
     const projects: CoveredProject[] = [projectA]
@@ -40,6 +40,16 @@ describe('buildMessage', () => {
     const result = buildMessage(projects, sha)
     expect(result).toEqual(expected2Projects)
   })
+
+  it("returns correct message when projects don't have coverage before", () => {
+    const projects: CoveredProject[] = [
+      { ...projectA, coverageBefore: undefined },
+      { ...projectB, coverageBefore: undefined }
+    ]
+    const sha = 'abcdef1234567890'
+    const result = buildMessage(projects, sha)
+    expect(result).toEqual(expected2ProjectsNoBefore)
+  })
 })
 
 const expected1Project = `# Coverage Report
@@ -89,6 +99,44 @@ Description B
 ![0% - fail](http://img.shields.io/badge/project__b-0.00%25-critical)    ➡️ 0.00%
 
 
+<details>
+<summary>Coverage Details for <strong>project_b</strong></summary>
+
+| File | Line Percentage | Line Count |
+| --- | --- | --- |
+
+</details>
+
+`
+
+const expected2ProjectsNoBefore = `# Coverage Report
+This is an automatic coverage report for abcdef12, proudly generated by [Dart Coverage Assistant](https://github.com/whynotmake-it/dart-coverage-assistant) 🎯🧪.
+
+## Monorepo coverage
+This repository contains 2 Dart projects. This is is the total coverage across all of them:
+
+![0% - fail](http://img.shields.io/badge/0.00%25-critical)    
+
+## \`project_a\`
+Description A
+
+![0% - fail](http://img.shields.io/badge/project__a-0.00%25-critical)    
+
+
+<details>
+<summary>Coverage Details for <strong>project_a</strong></summary>
+
+| File | Line Percentage | Line Count |
+| --- | --- | --- |
+
+</details>
+
+## \`project_b\`
+Description B
+
+![0% - fail](http://img.shields.io/badge/project__b-0.00%25-critical)    
+
+
 <details>
 <summary>Coverage Details for <strong>project_b</strong></summary>
 
diff --git a/dist/index.js b/dist/index.js
index 049f167..b5caed0 100644
--- a/dist/index.js
+++ b/dist/index.js
@@ -20452,7 +20452,10 @@ function getTotalPercentage(projects) {
 }
 exports.getTotalPercentage = getTotalPercentage;
 function getTotalPercentageBefore(projects) {
-    return getLineCoverage(getSectionSummaries(projects, 'coverageBefore'));
+    if (projects.some(p => p.coverageBefore !== undefined)) {
+        return getLineCoverage(getSectionSummaries(projects, 'coverageBefore'));
+    }
+    return undefined;
 }
 exports.getTotalPercentageBefore = getTotalPercentageBefore;
 function getSectionSummaries(projects, coverageKey) {
@@ -20711,7 +20714,7 @@ function buildBody(project) {
 }
 function buildDiffString(diff) {
     if (diff === undefined) {
-        return '-';
+        return '';
     }
     if (diff === 0) {
         return `➡️ ${diff.toFixed(2)}%`;
diff --git a/src/lcov.ts b/src/lcov.ts
index d2c309e..e39fd68 100644
--- a/src/lcov.ts
+++ b/src/lcov.ts
@@ -119,8 +119,11 @@ export function getTotalPercentage(
 
 export function getTotalPercentageBefore(
   projects: CoveredProject[]
-): LineCoverage {
-  return getLineCoverage(getSectionSummaries(projects, 'coverageBefore'))
+): LineCoverage | undefined {
+  if (projects.some(p => p.coverageBefore !== undefined)) {
+    return getLineCoverage(getSectionSummaries(projects, 'coverageBefore'))
+  }
+  return undefined
 }
 
 function getSectionSummaries(
diff --git a/src/message.ts b/src/message.ts
index 5fa2730..ea10b32 100644
--- a/src/message.ts
+++ b/src/message.ts
@@ -123,7 +123,7 @@ function buildBody(project: CoveredProject): string {
 
 function buildDiffString(diff: number | undefined): string {
   if (diff === undefined) {
-    return '-'
+    return ''
   }
   if (diff === 0) {
     return `➡️ ${diff.toFixed(2)}%`