diff --git a/2.4/alpine3.10/Dockerfile b/2.4/alpine3.10/Dockerfile
index 2e085145c..753b053fa 100644
--- a/2.4/alpine3.10/Dockerfile
+++ b/2.4/alpine3.10/Dockerfile
@@ -7,7 +7,7 @@ RUN apk add --no-cache \
 RUN set -eux; \
 	mkdir -p /usr/local/etc; \
 	{ \
-	echo 'install: --no-document'; \
+		echo 'install: --no-document'; \
 		echo 'update: --no-document'; \
 	} >> /usr/local/etc/gemrc
 
diff --git a/2.4/alpine3.9/Dockerfile b/2.4/alpine3.9/Dockerfile
index 21d5fa498..40c2fdbf8 100644
--- a/2.4/alpine3.9/Dockerfile
+++ b/2.4/alpine3.9/Dockerfile
@@ -7,7 +7,7 @@ RUN apk add --no-cache \
 RUN set -eux; \
 	mkdir -p /usr/local/etc; \
 	{ \
-	echo 'install: --no-document'; \
+		echo 'install: --no-document'; \
 		echo 'update: --no-document'; \
 	} >> /usr/local/etc/gemrc
 
diff --git a/2.5/alpine3.10/Dockerfile b/2.5/alpine3.10/Dockerfile
index ea5757c0e..7c1958cd7 100644
--- a/2.5/alpine3.10/Dockerfile
+++ b/2.5/alpine3.10/Dockerfile
@@ -7,7 +7,7 @@ RUN apk add --no-cache \
 RUN set -eux; \
 	mkdir -p /usr/local/etc; \
 	{ \
-	echo 'install: --no-document'; \
+		echo 'install: --no-document'; \
 		echo 'update: --no-document'; \
 	} >> /usr/local/etc/gemrc
 
diff --git a/2.5/alpine3.9/Dockerfile b/2.5/alpine3.9/Dockerfile
index 5c6459185..52d621602 100644
--- a/2.5/alpine3.9/Dockerfile
+++ b/2.5/alpine3.9/Dockerfile
@@ -7,7 +7,7 @@ RUN apk add --no-cache \
 RUN set -eux; \
 	mkdir -p /usr/local/etc; \
 	{ \
-	echo 'install: --no-document'; \
+		echo 'install: --no-document'; \
 		echo 'update: --no-document'; \
 	} >> /usr/local/etc/gemrc
 
diff --git a/2.6/alpine3.10/Dockerfile b/2.6/alpine3.10/Dockerfile
index a85a351e7..516b96f99 100644
--- a/2.6/alpine3.10/Dockerfile
+++ b/2.6/alpine3.10/Dockerfile
@@ -7,7 +7,7 @@ RUN apk add --no-cache \
 RUN set -eux; \
 	mkdir -p /usr/local/etc; \
 	{ \
-	echo 'install: --no-document'; \
+		echo 'install: --no-document'; \
 		echo 'update: --no-document'; \
 	} >> /usr/local/etc/gemrc
 
diff --git a/2.6/alpine3.9/Dockerfile b/2.6/alpine3.9/Dockerfile
index f2bb1fe0f..ad0a98ddb 100644
--- a/2.6/alpine3.9/Dockerfile
+++ b/2.6/alpine3.9/Dockerfile
@@ -7,7 +7,7 @@ RUN apk add --no-cache \
 RUN set -eux; \
 	mkdir -p /usr/local/etc; \
 	{ \
-	echo 'install: --no-document'; \
+		echo 'install: --no-document'; \
 		echo 'update: --no-document'; \
 	} >> /usr/local/etc/gemrc
 
diff --git a/2.7-rc/alpine3.10/Dockerfile b/2.7-rc/alpine3.10/Dockerfile
index d4a0f8ff9..1759627e6 100644
--- a/2.7-rc/alpine3.10/Dockerfile
+++ b/2.7-rc/alpine3.10/Dockerfile
@@ -7,7 +7,7 @@ RUN apk add --no-cache \
 RUN set -eux; \
 	mkdir -p /usr/local/etc; \
 	{ \
-	echo 'install: --no-document'; \
+		echo 'install: --no-document'; \
 		echo 'update: --no-document'; \
 	} >> /usr/local/etc/gemrc
 
diff --git a/Dockerfile-alpine.template b/Dockerfile-alpine.template
index 8c01af63f..ab6b53dc7 100644
--- a/Dockerfile-alpine.template
+++ b/Dockerfile-alpine.template
@@ -7,7 +7,7 @@ RUN apk add --no-cache \
 RUN set -eux; \
 	mkdir -p /usr/local/etc; \
 	{ \
-	echo 'install: --no-document'; \
+		echo 'install: --no-document'; \
 		echo 'update: --no-document'; \
 	} >> /usr/local/etc/gemrc