diff --git a/docs/content/showcase/balaramadurai.net.md b/docs/content/showcase/balaramadurai.net.md
index 08d5c0dc9..ca4a7c71e 100644
--- a/docs/content/showcase/balaramadurai.net.md
+++ b/docs/content/showcase/balaramadurai.net.md
@@ -7,6 +7,6 @@ sitelink: http://balaramadurai.net
 tags:
 - personal
 - blog
-thumbnail: /img/balaramadurai-net-tn.png
+thumbnail: /img/balaramadurai-net-tn.jpg
 title: Dr. Bala Ramadurai | Professor & Consultant in Innovation, Design Thinking and Tech Forecasting
 ---
diff --git a/docs/content/showcase/christianmendoza.md b/docs/content/showcase/christianmendoza.md
index 46f72e96c..6d18735d9 100644
--- a/docs/content/showcase/christianmendoza.md
+++ b/docs/content/showcase/christianmendoza.md
@@ -9,6 +9,6 @@ sourceLink: https://github.com/christianmendoza/christianmendoza.me
 tags:
 - personal
 - profile
-thumbnail: /img/christianmendoza-tn.png
+thumbnail: /img/christianmendoza-tn.jpg
 title: christianmendoza.me
 ---
diff --git a/docs/content/showcase/neavey.net.md b/docs/content/showcase/neavey.net.md
index d9a4bb654..443d2b670 100644
--- a/docs/content/showcase/neavey.net.md
+++ b/docs/content/showcase/neavey.net.md
@@ -9,6 +9,6 @@ tags:
 - personal
 - travel
 - blog
-thumbnail: /img/neavey-tn.png
+thumbnail: /img/neavey-tn.jpg
 title: neavey.net
 ---
diff --git a/docs/content/showcase/robertbasic.md b/docs/content/showcase/robertbasic.md
index f27cb8d85..237fce837 100644
--- a/docs/content/showcase/robertbasic.md
+++ b/docs/content/showcase/robertbasic.md
@@ -9,7 +9,7 @@ sourceLink: https://github.com/robertbasic/robertbasic.com-hugo
 tags:
 - personal
 - blog
-thumbnail: /img/robertbasic-tn.jpg
+thumbnail: /img/robertbasic-tn.png
 title: Robert Basic's blog
 ---
 
diff --git a/docs/content/showcase/stefano.chiodino.md b/docs/content/showcase/stefano.chiodino.md
index 1a6477a91..5880eb9ed 100644
--- a/docs/content/showcase/stefano.chiodino.md
+++ b/docs/content/showcase/stefano.chiodino.md
@@ -8,7 +8,7 @@ sourceLink: https://github.com/Draga/go-web
 tags:
 - personal
 - blog
-thumbnail: /img/stefano.chiodino-tn.png
+thumbnail: /img/stefano.chiodino-tn.jpg
 title: stefano.chiodino.uk
 ---
 
diff --git a/docs/content/showcase/thecodeking.md b/docs/content/showcase/thecodeking.md
index dc70f28cf..86786d736 100644
--- a/docs/content/showcase/thecodeking.md
+++ b/docs/content/showcase/thecodeking.md
@@ -7,7 +7,7 @@ sitelink: http://thecodeking.co.uk
 tags:
 - personal
 - blog
-thumbnail: /img/thecodeking-tn.png
+thumbnail: /img/thecodeking-tn.jpg
 title: thecodeking
 ---
 
diff --git a/docs/content/showcase/yulinling.net.md b/docs/content/showcase/yulinling.net.md
index e85a1ad2f..b5a6559f1 100644
--- a/docs/content/showcase/yulinling.net.md
+++ b/docs/content/showcase/yulinling.net.md
@@ -9,6 +9,6 @@ sourceLink: https://bitbucket.org/lynxiayel/yulinling_source_public
 tags:
 - blog
 - documentation
-thumbnail: /img/yulinling-tn.png
+thumbnail: /img/yulinling-tn.jpg
 title: <span lang="zh-CN">语林灵</span> (Yulinling)
 ---
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