diff --git i/config.def.h w/config.def.h
index 1edb647..5d312d2 100644
--- i/config.def.h
+++ w/config.def.h
@@ -21,3 +21,8 @@ static unsigned int lines      = 0;
  * for example: " /?\"&[]"
  */
 static const char worddelimiters[] = " ";
+
+/*
+ * Use prefix matching by default; can be inverted with the -x flag.
+ */
+static int use_prefix = 1;
diff --git i/dmenu.1 w/dmenu.1
index 323f93c..429fdfa 100644
--- i/dmenu.1
+++ w/dmenu.1
@@ -3,7 +3,7 @@
 dmenu \- dynamic menu
 .SH SYNOPSIS
 .B dmenu
-.RB [ \-bfiv ]
+.RB [ \-bfivx ]
 .RB [ \-l
 .IR lines ]
 .RB [ \-m
@@ -78,6 +78,9 @@ defines the selected foreground color.
 .B \-v
 prints version information to stdout, then exits.
 .TP
+.B \-x
+Invert prefix matching setting.
+.TP
 .BI \-w " windowid"
 embed into windowid.
 .SH USAGE
diff --git i/dmenu.c w/dmenu.c
index 6b8f51b..3cef454 100644
--- i/dmenu.c
+++ w/dmenu.c
@@ -228,8 +228,13 @@ match(void)
 			die("cannot realloc %u bytes:", tokn * sizeof *tokv);
 	len = tokc ? strlen(tokv[0]) : 0;
 
-	matches = lprefix = lsubstr = matchend = prefixend = substrend = NULL;
-	textsize = strlen(text) + 1;
+	if (use_prefix) {
+		matches = lprefix = matchend = prefixend = NULL;
+		textsize = strlen(text);
+	} else {
+		matches = lprefix = lsubstr = matchend = prefixend = substrend = NULL;
+		textsize = strlen(text) + 1;
+	}
 	for (item = items; item && item->text; item++) {
 		for (i = 0; i < tokc; i++)
 			if (!fstrstr(item->text, tokv[i]))
@@ -241,7 +246,7 @@ match(void)
 			appenditem(item, &matches, &matchend);
 		else if (!fstrncmp(tokv[0], item->text, len))
 			appenditem(item, &lprefix, &prefixend);
-		else
+		else if (!use_prefix)
 			appenditem(item, &lsubstr, &substrend);
 	}
 	if (lprefix) {
@@ -252,7 +257,7 @@ match(void)
 			matches = lprefix;
 		matchend = prefixend;
 	}
-	if (lsubstr) {
+	if (!use_prefix && lsubstr) {
 		if (matches) {
 			matchend->right = lsubstr;
 			lsubstr->left = matchend;
@@ -260,6 +265,7 @@ match(void)
 			matches = lsubstr;
 		matchend = substrend;
 	}
+
 	curr = sel = matches;
 	calcoffsets();
 }
@@ -309,6 +315,7 @@ keypress(XKeyEvent *ev)
 {
 	char buf[32];
 	int len;
+	struct item * item;
 	KeySym ksym;
 	Status status;
 
@@ -487,12 +494,17 @@ insert:
 		}
 		break;
 	case XK_Tab:
-		if (!sel)
-			return;
-		strncpy(text, sel->text, sizeof text - 1);
+		if (!matches) break; /* cannot complete no matches */
+		strncpy(text, matches->text, sizeof text - 1);
 		text[sizeof text - 1] = '\0';
-		cursor = strlen(text);
-		match();
+		len = cursor = strlen(text); /* length of longest common prefix */
+		for (item = matches; item && item->text; item = item->right) {
+			cursor = 0;
+			while (cursor < len && text[cursor] == item->text[cursor])
+				cursor++;
+			len = cursor;
+		}
+		memset(text + len, '\0', strlen(text) - len);
 		break;
 	}
 
@@ -682,7 +694,7 @@ setup(void)
 static void
 usage(void)
 {
-	fputs("usage: dmenu [-bfiv] [-l lines] [-p prompt] [-fn font] [-m monitor]\n"
+	fputs("usage: dmenu [-bfivx] [-l lines] [-p prompt] [-fn font] [-m monitor]\n"
 	      "             [-nb color] [-nf color] [-sb color] [-sf color] [-w windowid]\n", stderr);
 	exit(1);
 }
@@ -705,7 +717,9 @@ main(int argc, char *argv[])
 		else if (!strcmp(argv[i], "-i")) { /* case-insensitive item matching */
 			fstrncmp = strncasecmp;
 			fstrstr = cistrstr;
-		} else if (i + 1 == argc)
+		} else if (!strcmp(argv[i], "-x"))   /* invert use_prefix */
+			use_prefix = !use_prefix;
+		else if (i + 1 == argc)
 			usage();
 		/* these options take one argument */
 		else if (!strcmp(argv[i], "-l"))   /* number of lines in vertical list */