diff --git a/gdb/linespec.c b/gdb/linespec.c
index b96c79f..b35ac6a 100644
--- a/gdb/linespec.c
+++ b/gdb/linespec.c
@@ -43,6 +43,7 @@
 #include "arch-utils.h"
 #include <ctype.h>
 #include "cli/cli-utils.h"
+#include "filenames.h"
 
 /* Prototypes for local functions.  */
 
@@ -1216,10 +1217,16 @@ locate_first_half (char **argptr, int *is_quote_enclosed)
 	}
       /* Check for the end of the first half of the linespec.  End of
          line, a tab, a colon or a space.  But if enclosed in double
-	 quotes we do not break on enclosed spaces.  */
+	 quotes we do not break on enclosed spaces.
+
+	 Colons are especially problematic, since we don't really want to stop
+	 if the colon is part of a filename.  The simple heuristic used here
+	 is to keep going if the colon is followed by a directory separator.
+	 This will capture drive letters on Windows, but it will (still) fail
+	 for any filename containing ":", "::", ":/", or ":\\".  */
       if (!*p
 	  || p[0] == '\t'
-	  || (p[0] == ':')
+	  || (p[0] == ':' && !IS_DIR_SEPARATOR (p[1]))
 	  || ((p[0] == ' ') && !*is_quote_enclosed))
 	break;
       if (p[0] == '.' && strchr (p, ':') == NULL)
diff --git a/gdb/testsuite/gdb.base/ls-driveletter.exp b/gdb/testsuite/gdb.base/ls-driveletter.exp
new file mode 100644
index 0000000..66efd1f
--- /dev/null
+++ b/gdb/testsuite/gdb.base/ls-driveletter.exp
@@ -0,0 +1,26 @@
+# Copyright 2011 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+# Test linespecs containing drive letters.
+# PR gdb/12843
+
+# We don't actually need our own test case to test this, so grab
+# another one.
+
+if {[prepare_for_testing ls-driveletter.exp memattr memattr.c {debug}]} {
+  return -1
+}
+
+gdb_test "list c:/foo/bar/baz.c:1" "No source file named c:/foo/bar/baz.c."