diff --git a/doc/man/ruby-install.1.md b/doc/man/ruby-install.1.md
index f8e0a7be..618c89d0 100644
--- a/doc/man/ruby-install.1.md
+++ b/doc/man/ruby-install.1.md
@@ -182,6 +182,14 @@ Uninstall a Ruby version:
 *~/.rubies/$ruby-$version*
 	Default non-root user installation directory.
 
+## ENVIRONMENT
+
+*RUBY_INSTALL_SRC_DIR*
+  Overrides the default source directory.
+
+*RUBY_INSTALL_RUBIES_DIR*
+  Overrides the default installation directory.
+
 ## AUTHOR
 
 Postmodern <postmodern.mod3@gmail.com>
diff --git a/share/man/man1/ruby-install.1 b/share/man/man1/ruby-install.1
index d76bf1c0..323077dd 100644
--- a/share/man/man1/ruby-install.1
+++ b/share/man/man1/ruby-install.1
@@ -1,4 +1,4 @@
-.\" Generated by kramdown-man 0.1.7
+.\" Generated by kramdown-man 0.1.8
 .\" https://github.com/postmodern/kramdown-man#readme
 .TH ruby-install 1 "Aug 2018" ruby-install "User Manuals"
 .LP
@@ -265,6 +265,16 @@ Default root user installation directory\.
 \fI\[ti]\[sl]\.rubies\[sl]\[Do]ruby\-\[Do]version\fP
 Default non\-root user installation directory\.
 .LP
+.SH ENVIRONMENT
+.LP
+.TP
+\fIRUBY\[ru]INSTALL\[ru]SRC\[ru]DIR\fP
+Overrides the default source directory\.
+.LP
+.TP
+\fIRUBY\[ru]INSTALL\[ru]RUBIES\[ru]DIR\fP
+Overrides the default installation directory\.
+.LP
 .SH AUTHOR
 .LP
 .PP
diff --git a/share/ruby-install/ruby-install.sh b/share/ruby-install/ruby-install.sh
index cc4df76b..dfbf32c6 100644
--- a/share/ruby-install/ruby-install.sh
+++ b/share/ruby-install/ruby-install.sh
@@ -14,11 +14,11 @@ make_opts=()
 system_dir="/usr/local"
 
 if (( UID == 0 )); then
-	src_dir="$system_dir/src"
-	rubies_dir="/opt/rubies"
+	src_dir="${RUBY_INSTALL_SRC_DIR:-$system_dir/src}"
+	rubies_dir="${RUBY_INSTALL_RUBIES_DIR:-/opt/rubies}"
 else
-	src_dir="$HOME/src"
-	rubies_dir="$HOME/.rubies"
+	src_dir="${RUBY_INSTALL_SRC_DIR:-$HOME/src}"
+	rubies_dir="${RUBY_INSTALL_RUBIES_DIR:-$HOME/.rubies}"
 fi
 
 source "$ruby_install_dir/logging.sh"
diff --git a/test/ruby-install-tests/variables_test.sh b/test/ruby-install-tests/variables_test.sh
index 6b49ecd9..c28e9018 100755
--- a/test/ruby-install-tests/variables_test.sh
+++ b/test/ruby-install-tests/variables_test.sh
@@ -73,4 +73,26 @@ function test_rubies_dir()
 	fi
 }
 
+function test_src_dir_with_RUBY_INSTALL_SRC_DIR()
+{
+	export RUBY_INSTALL_SRC_DIR="/path/to/src/dir"
+	. ./share/ruby-install/ruby-install.sh
+
+	assertEquals "did not set \$src_dir to \$RUBY_INSTALL_SRC_DIR" \
+		     "$RUBY_INSTALL_SRC_DIR" "$src_dir"
+
+	unset RUBY_INSTALL_SRC_DIR
+}
+
+function test_rubies_dir_with_RUBY_INSTALL_SRC_DIR()
+{
+	export RUBY_INSTALL_RUBIES_DIR="/path/to/rubies/dir"
+	. ./share/ruby-install/ruby-install.sh
+
+	assertEquals "did not set \$rubies_dir to \$RUBY_INSTALL_RUBIES_DIR" \
+		     "$RUBY_INSTALL_RUBIES_DIR" "$rubies_dir"
+
+	unset RUBY_INSTALL_RUBIES_DIR
+}
+
 SHUNIT_PARENT=$0 . $SHUNIT2