diff --git a/config.c b/config.c
index c6b874a..48edc6a 100644
--- a/config.c
+++ b/config.c
@@ -201,11 +201,105 @@
 	strbuf_release(&env);
 }
 
+static inline int iskeychar(int c)
+{
+	return isalnum(c) || c == '-';
+}
+
+/*
+ * Auxiliary function to sanity-check and split the key into the section
+ * identifier and variable name.
+ *
+ * Returns 0 on success, -1 when there is an invalid character in the key and
+ * -2 if there is no section name in the key.
+ *
+ * store_key - pointer to char* which will hold a copy of the key with
+ *             lowercase section and variable name
+ * baselen - pointer to int which will hold the length of the
+ *           section + subsection part, can be NULL
+ */
+static int git_config_parse_key_1(const char *key, char **store_key, int *baselen_, int quiet)
+{
+	int i, dot, baselen;
+	const char *last_dot = strrchr(key, '.');
+
+	/*
+	 * Since "key" actually contains the section name and the real
+	 * key name separated by a dot, we have to know where the dot is.
+	 */
+
+	if (last_dot == NULL || last_dot == key) {
+		if (!quiet)
+			error("key does not contain a section: %s", key);
+		return -CONFIG_NO_SECTION_OR_NAME;
+	}
+
+	if (!last_dot[1]) {
+		if (!quiet)
+			error("key does not contain variable name: %s", key);
+		return -CONFIG_NO_SECTION_OR_NAME;
+	}
+
+	baselen = last_dot - key;
+	if (baselen_)
+		*baselen_ = baselen;
+
+	/*
+	 * Validate the key and while at it, lower case it for matching.
+	 */
+	if (store_key)
+		*store_key = xmallocz(strlen(key));
+
+	dot = 0;
+	for (i = 0; key[i]; i++) {
+		unsigned char c = key[i];
+		if (c == '.')
+			dot = 1;
+		/* Leave the extended basename untouched.. */
+		if (!dot || i > baselen) {
+			if (!iskeychar(c) ||
+			    (i == baselen + 1 && !isalpha(c))) {
+				if (!quiet)
+					error("invalid key: %s", key);
+				goto out_free_ret_1;
+			}
+			c = tolower(c);
+		} else if (c == '\n') {
+			if (!quiet)
+				error("invalid key (newline): %s", key);
+			goto out_free_ret_1;
+		}
+		if (store_key)
+			(*store_key)[i] = c;
+	}
+
+	return 0;
+
+out_free_ret_1:
+	if (store_key) {
+		free(*store_key);
+		*store_key = NULL;
+	}
+	return -CONFIG_INVALID_KEY;
+}
+
+int git_config_parse_key(const char *key, char **store_key, int *baselen)
+{
+	return git_config_parse_key_1(key, store_key, baselen, 0);
+}
+
+int git_config_key_is_valid(const char *key)
+{
+	return !git_config_parse_key_1(key, NULL, NULL, 1);
+}
+
 int git_config_parse_parameter(const char *text,
 			       config_fn_t fn, void *data)
 {
 	const char *value;
+	char *canonical_name;
 	struct strbuf **pair;
+	int ret;
 
 	pair = strbuf_split_str(text, '=', 2);
 	if (!pair[0])
@@ -223,13 +317,15 @@
 		strbuf_list_free(pair);
 		return error("bogus config parameter: %s", text);
 	}
-	strbuf_tolower(pair[0]);
-	if (fn(pair[0]->buf, value, data) < 0) {
-		strbuf_list_free(pair);
-		return -1;
+
+	if (git_config_parse_key(pair[0]->buf, &canonical_name, NULL)) {
+		ret = -1;
+	} else {
+		ret = (fn(canonical_name, value, data) < 0) ? -1 : 0;
+		free(canonical_name);
 	}
 	strbuf_list_free(pair);
-	return 0;
+	return ret;
 }
 
 int git_config_from_parameters(config_fn_t fn, void *data)
@@ -356,11 +452,6 @@
 	}
 }
 
-static inline int iskeychar(int c)
-{
-	return isalnum(c) || c == '-';
-}
-
 static int get_value(config_fn_t fn, void *data, struct strbuf *name)
 {
 	int c;
@@ -1990,93 +2081,6 @@
 }
 
 /*
- * Auxiliary function to sanity-check and split the key into the section
- * identifier and variable name.
- *
- * Returns 0 on success, -1 when there is an invalid character in the key and
- * -2 if there is no section name in the key.
- *
- * store_key - pointer to char* which will hold a copy of the key with
- *             lowercase section and variable name
- * baselen - pointer to int which will hold the length of the
- *           section + subsection part, can be NULL
- */
-static int git_config_parse_key_1(const char *key, char **store_key, int *baselen_, int quiet)
-{
-	int i, dot, baselen;
-	const char *last_dot = strrchr(key, '.');
-
-	/*
-	 * Since "key" actually contains the section name and the real
-	 * key name separated by a dot, we have to know where the dot is.
-	 */
-
-	if (last_dot == NULL || last_dot == key) {
-		if (!quiet)
-			error("key does not contain a section: %s", key);
-		return -CONFIG_NO_SECTION_OR_NAME;
-	}
-
-	if (!last_dot[1]) {
-		if (!quiet)
-			error("key does not contain variable name: %s", key);
-		return -CONFIG_NO_SECTION_OR_NAME;
-	}
-
-	baselen = last_dot - key;
-	if (baselen_)
-		*baselen_ = baselen;
-
-	/*
-	 * Validate the key and while at it, lower case it for matching.
-	 */
-	if (store_key)
-		*store_key = xmallocz(strlen(key));
-
-	dot = 0;
-	for (i = 0; key[i]; i++) {
-		unsigned char c = key[i];
-		if (c == '.')
-			dot = 1;
-		/* Leave the extended basename untouched.. */
-		if (!dot || i > baselen) {
-			if (!iskeychar(c) ||
-			    (i == baselen + 1 && !isalpha(c))) {
-				if (!quiet)
-					error("invalid key: %s", key);
-				goto out_free_ret_1;
-			}
-			c = tolower(c);
-		} else if (c == '\n') {
-			if (!quiet)
-				error("invalid key (newline): %s", key);
-			goto out_free_ret_1;
-		}
-		if (store_key)
-			(*store_key)[i] = c;
-	}
-
-	return 0;
-
-out_free_ret_1:
-	if (store_key) {
-		free(*store_key);
-		*store_key = NULL;
-	}
-	return -CONFIG_INVALID_KEY;
-}
-
-int git_config_parse_key(const char *key, char **store_key, int *baselen)
-{
-	return git_config_parse_key_1(key, store_key, baselen, 0);
-}
-
-int git_config_key_is_valid(const char *key)
-{
-	return !git_config_parse_key_1(key, NULL, NULL, 1);
-}
-
-/*
  * If value==NULL, unset in (remove from) config,
  * if value_regex!=NULL, disregard key/value pairs where value does not match.
  * if value_regex==CONFIG_REGEX_NONE, do not match any existing values
diff --git a/t/t1300-repo-config.sh b/t/t1300-repo-config.sh
index 052f120..afcca0d 100755
--- a/t/t1300-repo-config.sh
+++ b/t/t1300-repo-config.sh
@@ -1097,6 +1097,68 @@
 	test_cmp expect actual
 '
 
+test_expect_success 'last one wins: two level vars' '
+
+	# sec.var and sec.VAR are the same variable, as the first
+	# and the last level of a configuration variable name is
+	# case insensitive.
+
+	echo VAL >expect &&
+
+	git -c sec.var=val -c sec.VAR=VAL config --get sec.var >actual &&
+	test_cmp expect actual &&
+	git -c SEC.var=val -c sec.var=VAL config --get sec.var >actual &&
+	test_cmp expect actual &&
+
+	git -c sec.var=val -c sec.VAR=VAL config --get SEC.var >actual &&
+	test_cmp expect actual &&
+	git -c SEC.var=val -c sec.var=VAL config --get sec.VAR >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'last one wins: three level vars' '
+
+	# v.a.r and v.A.r are not the same variable, as the middle
+	# level of a three-level configuration variable name is
+	# case sensitive.
+
+	echo val >expect &&
+	git -c v.a.r=val -c v.A.r=VAL config --get v.a.r >actual &&
+	test_cmp expect actual &&
+	git -c v.a.r=val -c v.A.r=VAL config --get V.a.R >actual &&
+	test_cmp expect actual &&
+
+	# v.a.r and V.a.R are the same variable, as the first
+	# and the last level of a configuration variable name is
+	# case insensitive.
+
+	echo VAL >expect &&
+	git -c v.a.r=val -c v.a.R=VAL config --get v.a.r >actual &&
+	test_cmp expect actual &&
+	git -c v.a.r=val -c V.a.r=VAL config --get v.a.r >actual &&
+	test_cmp expect actual &&
+	git -c v.a.r=val -c v.a.R=VAL config --get V.a.R >actual &&
+	test_cmp expect actual &&
+	git -c v.a.r=val -c V.a.r=VAL config --get V.a.R >actual &&
+	test_cmp expect actual
+'
+
+for VAR in a .a a. a.0b a."b c". a."b c".0d
+do
+	test_expect_success "git -c $VAR=VAL rejects invalid '$VAR'" '
+		test_must_fail git -c "$VAR=VAL" config -l
+	'
+done
+
+for VAR in a.b a."b c".d
+do
+	test_expect_success "git -c $VAR=VAL works with valid '$VAR'" '
+		echo VAL >expect &&
+		git -c "$VAR=VAL" config --get "$VAR" >actual &&
+		test_cmp expect actual
+	'
+done
+
 test_expect_success 'git -c is not confused by empty environment' '
 	GIT_CONFIG_PARAMETERS="" git -c x.one=1 config --list
 '