diff --git a/Documentation/gitattributes.txt b/Documentation/gitattributes.txt
index ed03e2a4aa82d5466901dc7f4048aee78a267d8a..c80ca5da4387e44f42b3bfd54132efc1def881b6 100644
--- a/Documentation/gitattributes.txt
+++ b/Documentation/gitattributes.txt
@@ -484,6 +484,8 @@ patterns are available:
 
 - `csharp` suitable for source code in the C# language.
 
+- `fortran` suitable for source code in the Fortran language.
+
 - `html` suitable for HTML/XHTML documents.
 
 - `java` suitable for source code in the Java language.
diff --git a/t/t4018-diff-funcname.sh b/t/t4018-diff-funcname.sh
index c8e19372b00f128646b809e1f5723d88b58a3f30..0a61b57b5f6f00ae4c0734a34ce45c0ba1fcf098 100755
--- a/t/t4018-diff-funcname.sh
+++ b/t/t4018-diff-funcname.sh
@@ -32,7 +32,7 @@ EOF
 
 sed 's/beer\\/beer,\\/' < Beer.java > Beer-correct.java
 
-builtin_patterns="bibtex cpp csharp html java objc pascal php python ruby tex"
+builtin_patterns="bibtex cpp csharp fortran html java objc pascal php python ruby tex"
 for p in $builtin_patterns
 do
 	test_expect_success "builtin $p pattern compiles" '
diff --git a/userdiff.c b/userdiff.c
index e5522159b362811346b4306246391e960a4e7041..f9e05b548c2fdbc349a1d47d81619e266ec9fb83 100644
--- a/userdiff.c
+++ b/userdiff.c
@@ -9,7 +9,23 @@ static int drivers_alloc;
 
 #define PATTERNS(name, pattern, word_regex)			\
 	{ name, NULL, -1, { pattern, REG_EXTENDED }, word_regex }
+#define IPATTERN(name, pattern, word_regex)			\
+	{ name, NULL, -1, { pattern, REG_EXTENDED | REG_ICASE }, word_regex }
 static struct userdiff_driver builtin_drivers[] = {
+IPATTERN("fortran",
+	 "!^([C*]|[ \t]*!)\n"
+	 "!^[ \t]*MODULE[ \t]+PROCEDURE[ \t]\n"
+	 "^[ \t]*((END[ \t]+)?(PROGRAM|MODULE|BLOCK[ \t]+DATA"
+		"|([^'\" \t]+[ \t]+)*(SUBROUTINE|FUNCTION))[ \t]+[A-Z].*)$",
+	 /* -- */
+	 "[a-zA-Z][a-zA-Z0-9_]*"
+	 "|\\.([Ee][Qq]|[Nn][Ee]|[Gg][TtEe]|[Ll][TtEe]|[Tt][Rr][Uu][Ee]|[Ff][Aa][Ll][Ss][Ee]|[Aa][Nn][Dd]|[Oo][Rr]|[Nn]?[Ee][Qq][Vv]|[Nn][Oo][Tt])\\."
+	 /* numbers and format statements like 2E14.4, or ES12.6, 9X.
+	  * Don't worry about format statements without leading digits since
+	  * they would have been matched above as a variable anyway. */
+	 "|[-+]?[0-9.]+([AaIiDdEeFfLlTtXx][Ss]?[-+]?[0-9.]*)?(_[a-zA-Z0-9][a-zA-Z0-9_]*)?"
+	 "|//|\\*\\*|::|[/<>=]="
+	 "|[^[:space:]]|[\x80-\xff]+"),
 PATTERNS("html", "^[ \t]*(<[Hh][1-6][ \t].*>.*)$",
 	 "[^<>= \t]+|[^[:space:]]|[\x80-\xff]+"),
 PATTERNS("java",
@@ -101,6 +117,7 @@ PATTERNS("csharp",
 { "default", NULL, -1, { NULL, 0 } },
 };
 #undef PATTERNS
+#undef IPATTERN
 
 static struct userdiff_driver driver_true = {
 	"diff=true",