diff --git a/t/t4018-diff-funcname.sh b/t/t4018-diff-funcname.sh
index 008325f2a8..5ac744f397 100755
--- a/t/t4018-diff-funcname.sh
+++ b/t/t4018-diff-funcname.sh
@@ -30,12 +30,19 @@ public class Beer
 EOF
 sed 's/beer\\/beer,\\/' <Beer.java >Beer-correct.java
 
-test_expect_funcname () {
-	lang=${2-java}
-	test_expect_code 1 git diff --no-index -U1 \
-		"Beer.$lang" "Beer-correct.$lang" >diff &&
-	grep "^@@.*@@ $1" diff
-}
+test_expect_success 'setup' '
+	# a non-trivial custom pattern
+	git config diff.custom1.funcname "!static
+!String
+[^ 	].*s.*" &&
+
+	# a custom pattern which matches to end of line
+	git config diff.custom2.funcname "......Beer\$" &&
+
+	# alternation in pattern
+	git config diff.custom3.funcname "Beer$" &&
+	git config diff.custom3.xfuncname "^[ 	]*((public|static).*)$"
+'
 
 diffpatterns="
 	ada
@@ -53,6 +60,9 @@ diffpatterns="
 	python
 	ruby
 	tex
+	custom1
+	custom2
+	custom3
 "
 
 for p in $diffpatterns
@@ -79,30 +89,12 @@ test_expect_success 'set up .gitattributes declaring drivers to test' '
 	EOF
 '
 
-test_expect_success 'custom pattern' '
-	test_config diff.java.funcname "!static
-!String
-[^ 	].*s.*" &&
-	test_expect_funcname "int special;\$"
-'
-
 test_expect_success 'last regexp must not be negated' '
 	test_config diff.java.funcname "!static" &&
 	test_expect_code 128 git diff --no-index Beer.java Beer-correct.java 2>msg &&
 	grep ": Last expression must not be negated:" msg
 '
 
-test_expect_success 'pattern which matches to end of line' '
-	test_config diff.java.funcname "Beer\$" &&
-	test_expect_funcname "Beer\$"
-'
-
-test_expect_success 'alternation in pattern' '
-	test_config diff.java.funcname "Beer$" &&
-	test_config diff.java.xfuncname "^[ 	]*((public|static).*)$" &&
-	test_expect_funcname "public static void main("
-'
-
 test_expect_success 'setup hunk header tests' '
 	for i in $diffpatterns
 	do
diff --git a/t/t4018/custom1-pattern b/t/t4018/custom1-pattern
new file mode 100644
index 0000000000..e8fd59f884
--- /dev/null
+++ b/t/t4018/custom1-pattern
@@ -0,0 +1,17 @@
+public class Beer
+{
+	int special, RIGHT;
+	public static void main(String args[])
+	{
+		String s=" ";
+		for(int x = 99; x > 0; x--)
+		{
+			System.out.print(x + " bottles of beer on the wall "
+				+ x + " bottles of beer\n" // ChangeMe
+				+ "Take one down, pass it around, " + (x - 1)
+				+ " bottles of beer on the wall.\n");
+		}
+		System.out.print("Go to the store, buy some more,\n"
+			+ "99 bottles of beer on the wall.\n");
+	}
+}
diff --git a/t/t4018/custom2-match-to-end-of-line b/t/t4018/custom2-match-to-end-of-line
new file mode 100644
index 0000000000..f88ac318b7
--- /dev/null
+++ b/t/t4018/custom2-match-to-end-of-line
@@ -0,0 +1,8 @@
+public class RIGHT_Beer
+{
+	int special;
+	public static void main(String args[])
+	{
+		System.out.print("ChangeMe");
+	}
+}
diff --git a/t/t4018/custom3-alternation-in-pattern b/t/t4018/custom3-alternation-in-pattern
new file mode 100644
index 0000000000..5f3769c64f
--- /dev/null
+++ b/t/t4018/custom3-alternation-in-pattern
@@ -0,0 +1,17 @@
+public class Beer
+{
+	int special;
+	public static void main(String RIGHT[])
+	{
+		String s=" ";
+		for(int x = 99; x > 0; x--)
+		{
+			System.out.print(x + " bottles of beer on the wall "
+				+ x + " bottles of beer\n" // ChangeMe
+				+ "Take one down, pass it around, " + (x - 1)
+				+ " bottles of beer on the wall.\n");
+		}
+		System.out.print("Go to the store, buy some more,\n"
+			+ "99 bottles of beer on the wall.\n");
+	}
+}