diff --git a/Tmain/abnormal-output-file-names.d/input.c b/Tmain/abnormal-output-file-names.d/input.c
new file mode 100644
index 0000000000..6d1a0d47b7
--- /dev/null
+++ b/Tmain/abnormal-output-file-names.d/input.c
@@ -0,0 +1 @@
+int x;
diff --git a/Tmain/abnormal-output-file-names.d/run.sh b/Tmain/abnormal-output-file-names.d/run.sh
new file mode 100644
index 0000000000..b15a766c1a
--- /dev/null
+++ b/Tmain/abnormal-output-file-names.d/run.sh
@@ -0,0 +1,39 @@
+# Copyright: 2016 Masatake YAMATO
+# License: GPL-2
+
+CTAGS=$1
+
+rm -f ./"'"
+rm -f ./'"'
+rm -f ./'$(ls)'
+rm -f ./'a b'
+
+${CTAGS} --quiet --options=NONE -o ./"'" --extra=-pF input.c
+${CTAGS} --quiet --options=NONE -o ./'"' --extra=-pF input.c
+${CTAGS} --quiet --options=NONE -o ./'$(ls)' --extra=-pF input.c
+${CTAGS} --quiet --options=NONE -o ./'a b' --extra=-pF input.c
+
+echo '#' SINGLE QUOTE
+if [ -e "'" ]; then
+	cat "'"
+fi
+
+echo '#' DOUBLE QUOTES
+if [ -e '"' ]; then
+	cat '"'
+fi
+
+echo '#' PROCESS SUBSTITUTION
+if [ -e '$(ls)' ]; then
+	cat '$(ls)'
+fi
+
+echo '#' SPACE
+if [ -e 'a b' ]; then
+	cat 'a b'
+fi
+
+rm -f ./"'"
+rm -f ./'"'
+rm -f ./'$(ls)'
+rm -f ./'a b'
diff --git a/Tmain/abnormal-output-file-names.d/stderr-expected.txt b/Tmain/abnormal-output-file-names.d/stderr-expected.txt
new file mode 100644
index 0000000000..e69de29bb2
diff --git a/Tmain/abnormal-output-file-names.d/stdout-expected.txt b/Tmain/abnormal-output-file-names.d/stdout-expected.txt
new file mode 100644
index 0000000000..5d1129ea84
--- /dev/null
+++ b/Tmain/abnormal-output-file-names.d/stdout-expected.txt
@@ -0,0 +1,8 @@
+# SINGLE QUOTE
+x	input.c	/^int x;$/;"	v	typeref:typename:int
+# DOUBLE QUOTES
+x	input.c	/^int x;$/;"	v	typeref:typename:int
+# PROCESS SUBSTITUTION
+x	input.c	/^int x;$/;"	v	typeref:typename:int
+# SPACE
+x	input.c	/^int x;$/;"	v	typeref:typename:int
diff --git a/main/sort.c b/main/sort.c
index 7ee7ce0a23..46ffd48a3d 100644
--- a/main/sort.c
+++ b/main/sort.c
@@ -55,17 +55,44 @@ extern void catFile (MIO *mio)
 # define PE_CONST const
 #endif
 
+/*
+   Output file name should not be evaluated in system(3) function.
+   The name must be used as is. Quotations are required to block the
+   evaluation.
+
+   Normal single-quotes are used to quote a cstring:
+   a => 'a'
+   " => '"'
+
+   If a single-quote is included in the cstring, use double quotes for quoting it.
+   ' => ''"'"''
+*/
+static void appendCstringWithQuotes (vString *dest, const char* cstr)
+{
+	const char* o;
+
+	vStringPut (dest, '\'');
+	for (o = cstr; *o; o++)
+	{
+		if (*o == '\'')
+			vStringCatS (dest, "'\"'\"'");
+		else
+			vStringPut (dest, *o);
+	}
+	vStringPut (dest, '\'');
+}
+
 extern void externalSortTags (const bool toStdout, MIO *tagFile)
 {
 	const char *const sortNormalCommand = "sort -u";
 	const char *const sortFoldedCommand = "sort -u -f";
 	const char *sortCommand =
 		Option.sorted == SO_FOLDSORTED ? sortFoldedCommand : sortNormalCommand;
+# ifndef HAVE_SETENV
 	PE_CONST char *const sortOrder1 = "LC_COLLATE=C";
 	PE_CONST char *const sortOrder2 = "LC_ALL=C";
-	const size_t length = 4 + strlen (sortOrder1) + strlen (sortOrder2) +
-			strlen (sortCommand) + (2 * strlen (tagFileName ()));
-	char *const cmd = (char *) malloc (length + 1);
+# endif
+	vString *cmd = vStringNew ();
 	int ret = -1;
 
 	if (cmd != NULL)
@@ -80,19 +107,29 @@ extern void externalSortTags (const bool toStdout, MIO *tagFile)
 		putenv (sortOrder1);
 		putenv (sortOrder2);
 # endif
-		if (toStdout)
-			sprintf (cmd, "%s", sortCommand);
-		else
-			sprintf (cmd, "%s -o %s %s", sortCommand,
-					tagFileName (), tagFileName ());
+		vStringCatS (cmd, sortCommand);
+		if (! toStdout)
+		{
+			vStringCatS (cmd, " -o ");
+			appendCstringWithQuotes (cmd, tagFileName ());
+			vStringPut (cmd, ' ');
+			appendCstringWithQuotes (cmd, tagFileName ());
+		}
 #else
-		if (toStdout)
-			sprintf (cmd, "%s %s %s", sortOrder1, sortOrder2, sortCommand);
-		else
-			sprintf (cmd, "%s %s %s -o %s %s", sortOrder1, sortOrder2,
-					sortCommand, tagFileName (), tagFileName ());
+		vStringCatS (cmd, sortOrder1);
+		vStringPut (cmd, ' ');
+		vStringCatS (cmd, sortOrder2);
+		vStringPut (cmd, ' ');
+		vStringCatS (cmd, sortCommand);
+		if (! toStdout)
+		{
+			vStringCats (cmd, " -o ");
+			appendCstringWithQuotes (cmd, tagFileName ());
+			vStringPut (cmd, ' ');
+			appendCstringWithQuotes (cmd, tagFileName ());
+		}
 #endif
-		verbose ("system (\"%s\")\n", cmd);
+		verbose ("system (\"%s\")\n", vStringValue (cmd));
 		if (toStdout)
 		{
 			const int fdstdin = 0;
@@ -105,15 +142,14 @@ extern void externalSortTags (const bool toStdout, MIO *tagFile)
 				error (FATAL | PERROR, "cannot redirect stdin");
 			if (lseek (fdstdin, 0, SEEK_SET) != 0)
 				error (FATAL | PERROR, "cannot rewind tag file");
-			ret = system (cmd);
+			ret = system (vStringValue (cmd));
 			if (dup2 (fdsave, fdstdin) < 0)
 				error (FATAL | PERROR, "cannot restore stdin fd");
 			close (fdsave);
 		}
 		else
-			ret = system (cmd);
-		free (cmd);
-
+			ret = system (vStringValue (cmd));
+		vStringDelete (cmd);
 	}
 	if (ret != 0)
 		error (FATAL | PERROR, "cannot sort tag file");