diff --git a/builtin/config.c b/builtin/config.c
index b8b18e3c94b5730afb343089821e8e622a5b00ee..f87443698a2b572e0d6d5e322905d78a907c8b86 100644
--- a/builtin/config.c
+++ b/builtin/config.c
@@ -153,7 +153,6 @@ static int show_config(const char *key_, const char *value_, void *cb)
 static int get_value(const char *key_, const char *regex_)
 {
 	int ret = -1;
-	char *tl;
 	char *global = NULL, *repo_config = NULL;
 	const char *system_wide = NULL, *local;
 
@@ -167,18 +166,32 @@ static int get_value(const char *key_, const char *regex_)
 			system_wide = git_etc_gitconfig();
 	}
 
-	key = xstrdup(key_);
-	for (tl=key+strlen(key)-1; tl >= key && *tl != '.'; --tl)
-		*tl = tolower(*tl);
-	for (tl=key; *tl && *tl != '.'; ++tl)
-		*tl = tolower(*tl);
-
 	if (use_key_regexp) {
+		char *tl;
+
+		/*
+		 * NEEDSWORK: this naive pattern lowercasing obviously does not
+		 * work for more complex patterns like "^[^.]*Foo.*bar".
+		 * Perhaps we should deprecate this altogether someday.
+		 */
+
+		key = xstrdup(key_);
+		for (tl = key + strlen(key) - 1;
+		     tl >= key && *tl != '.';
+		     tl--)
+			*tl = tolower(*tl);
+		for (tl = key; *tl && *tl != '.'; tl++)
+			*tl = tolower(*tl);
+
 		key_regexp = (regex_t*)xmalloc(sizeof(regex_t));
 		if (regcomp(key_regexp, key, REG_EXTENDED)) {
 			fprintf(stderr, "Invalid key pattern: %s\n", key_);
+			free(key);
 			goto free_strings;
 		}
+	} else {
+		if (git_config_parse_key(key_, &key, NULL))
+			goto free_strings;
 	}
 
 	if (regex_) {
diff --git a/cache.h b/cache.h
index f2dabefd9d75fddf0eb48e42a0907db6ac162b08..e637ca8e01a4a42044e217f4d2bcecabbee7c3b1 100644
--- a/cache.h
+++ b/cache.h
@@ -999,6 +999,7 @@ extern int git_config_maybe_bool(const char *, const char *);
 extern int git_config_string(const char **, const char *, const char *);
 extern int git_config_pathname(const char **, const char *, const char *);
 extern int git_config_set(const char *, const char *);
+extern int git_config_parse_key(const char *, char **, int *);
 extern int git_config_set_multivar(const char *, const char *, const char *, int);
 extern int git_config_rename_section(const char *, const char *);
 extern const char *git_etc_gitconfig(void);
diff --git a/config.c b/config.c
index 822ef8365ce29c48e4b04fcccc47ba2e0b3a255f..fa740a6a60a49512b613f70add97d445f622afd2 100644
--- a/config.c
+++ b/config.c
@@ -1092,6 +1092,75 @@ int git_config_set(const char *key, const char *value)
 	return git_config_set_multivar(key, value, NULL, 0);
 }
 
+/*
+ * 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
+ */
+int git_config_parse_key(const char *key, char **store_key, int *baselen_)
+{
+	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) {
+		error("key does not contain a section: %s", key);
+		return -2;
+	}
+
+	if (!last_dot[1]) {
+		error("key does not contain variable name: %s", key);
+		return -2;
+	}
+
+	baselen = last_dot - key;
+	if (baselen_)
+		*baselen_ = baselen;
+
+	/*
+	 * Validate the key and while at it, lower case it for matching.
+	 */
+	*store_key = xmalloc(strlen(key) + 1);
+
+	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))) {
+				error("invalid key: %s", key);
+				goto out_free_ret_1;
+			}
+			c = tolower(c);
+		} else if (c == '\n') {
+			error("invalid key (newline): %s", key);
+			goto out_free_ret_1;
+		}
+		(*store_key)[i] = c;
+	}
+	(*store_key)[i] = 0;
+
+	return 0;
+
+out_free_ret_1:
+	free(*store_key);
+	return -1;
+}
+
 /*
  * If value==NULL, unset in (remove from) config,
  * if value_regex!=NULL, disregard key/value pairs where value does not match.
@@ -1118,59 +1187,23 @@ int git_config_set(const char *key, const char *value)
 int git_config_set_multivar(const char *key, const char *value,
 	const char *value_regex, int multi_replace)
 {
-	int i, dot;
 	int fd = -1, in_fd;
 	int ret;
 	char *config_filename;
 	struct lock_file *lock = NULL;
-	const char *last_dot = strrchr(key, '.');
 
 	if (config_exclusive_filename)
 		config_filename = xstrdup(config_exclusive_filename);
 	else
 		config_filename = git_pathdup("config");
 
-	/*
-	 * 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) {
-		error("key does not contain a section: %s", key);
-		ret = 2;
+	/* parse-key returns negative; flip the sign to feed exit(3) */
+	ret = 0 - git_config_parse_key(key, &store.key, &store.baselen);
+	if (ret)
 		goto out_free;
-	}
-	store.baselen = last_dot - key;
 
 	store.multi_replace = multi_replace;
 
-	/*
-	 * Validate the key and while at it, lower case it for matching.
-	 */
-	store.key = xmalloc(strlen(key) + 1);
-	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 > store.baselen) {
-			if (!iskeychar(c) || (i == store.baselen+1 && !isalpha(c))) {
-				error("invalid key: %s", key);
-				free(store.key);
-				ret = 1;
-				goto out_free;
-			}
-			c = tolower(c);
-		} else if (c == '\n') {
-			error("invalid key (newline): %s", key);
-			free(store.key);
-			ret = 1;
-			goto out_free;
-		}
-		store.key[i] = c;
-	}
-	store.key[i] = 0;
 
 	/*
 	 * The lock serves a purpose in addition to locking: the new
diff --git a/t/t1300-repo-config.sh b/t/t1300-repo-config.sh
index d0e55465ff08698376f5d9fa86357d51bd57458c..53fb8228cf18e2b58f3ea63e98a0220fa0fd39f2 100755
--- a/t/t1300-repo-config.sh
+++ b/t/t1300-repo-config.sh
@@ -876,11 +876,25 @@ test_expect_success 'check split_cmdline return' "
 	"
 
 test_expect_success 'git -c "key=value" support' '
-	test "z$(git -c name=value config name)" = zvalue &&
 	test "z$(git -c core.name=value config core.name)" = zvalue &&
-	test "z$(git -c CamelCase=value config camelcase)" = zvalue &&
-	test "z$(git -c flag config --bool flag)" = ztrue &&
-	test_must_fail git -c core.name=value config name
+	test "z$(git -c foo.CamelCase=value config foo.camelcase)" = zvalue &&
+	test "z$(git -c foo.flag config --bool foo.flag)" = ztrue &&
+	test_must_fail git -c name=value config core.name
+'
+
+test_expect_success 'key sanity-checking' '
+	test_must_fail git config foo=bar &&
+	test_must_fail git config foo=.bar &&
+	test_must_fail git config foo.ba=r &&
+	test_must_fail git config foo.1bar &&
+	test_must_fail git config foo."ba
+				z".bar &&
+	test_must_fail git config . false &&
+	test_must_fail git config .foo false &&
+	test_must_fail git config foo. false &&
+	test_must_fail git config .foo. false &&
+	git config foo.bar true &&
+	git config foo."ba =z".bar false
 '
 
 test_done