diff --git a/usr.bin/whereis/whereis.1 b/usr.bin/whereis/whereis.1
--- a/usr.bin/whereis/whereis.1
+++ b/usr.bin/whereis/whereis.1
@@ -74,6 +74,10 @@
 .Pa /usr/src
 and
 .Pa /usr/ports .
+If the environment variable
+.Ev PORTSDIR
+is defined and points to a directory then all its subdirectories
+are included in the search of program sources.
 .Pp
 The following options are available:
 .Bl -tag -width indent
diff --git a/usr.bin/whereis/whereis.c b/usr.bin/whereis/whereis.c
--- a/usr.bin/whereis/whereis.c
+++ b/usr.bin/whereis/whereis.c
@@ -312,23 +312,35 @@
 			abort();
 		nele = 0;
 		decolonify(b, &sourcedirs, &nele);
-
-		if (stat(PATH_PORTS, &sb) == -1) {
+		ccharp path_ports;
+		if ((cp = getenv("PORTSDIR")) != NULL) {
+			b = strdup(cp);
+			if (b == NULL)
+				abort();
+		}
+		ccharp ports_locations[2] = {PATH_PORTS, cp};
+		int i;
+		for (i = 0; i < 2; i++) {
+			
+		path_ports = ports_locations[i];
+		if (!path_ports)
+			continue;
+		if (stat(path_ports, &sb) == -1) {
 			if (errno == ENOENT)
 				/* no /usr/ports, we are done */
-				return;
-			err(EX_OSERR, "stat(" PATH_PORTS ")");
+				continue;
+			err(EX_OSERR, "stat(%s)", path_ports);
 		}
 		if ((sb.st_mode & S_IFMT) != S_IFDIR)
-			/* /usr/ports is not a directory, ignore */
-			return;
-		if (access(PATH_PORTS, R_OK | X_OK) != 0)
-			return;
-		if ((dir = opendir(PATH_PORTS)) == NULL)
-			err(EX_OSERR, "opendir" PATH_PORTS ")");
+			/* This is not a directory, ignore */
+			continue;
+		if (access(path_ports, R_OK | X_OK) != 0)
+			continue;
+		if ((dir = opendir(path_ports)) == NULL)
+			err(EX_OSERR, "opendir %s)", path_ports);
 		while ((dirp = readdir(dir)) != NULL) {
 			/*
-			 * Not everything below PATH_PORTS is of
+			 * Not everything below path_ports is of
 			 * interest.  First, all dot files and
 			 * directories (e. g. .snap) can be ignored.
 			 * Also, all subdirectories starting with a
@@ -350,10 +362,10 @@
 			    (dirp->d_name[0] >= 'A' && dirp->d_name[0] <= 'Z') ||
 			    strcmp(dirp->d_name, "distfiles") == 0)
 				continue;
-			if ((b = malloc(sizeof PATH_PORTS + 1 + dirp->d_namlen))
+			if ((b = malloc(strlen(path_ports) + 1 + dirp->d_namlen))
 			    == NULL)
 				abort();
-			strcpy(b, PATH_PORTS);
+			strcpy(b, path_ports);
 			strcat(b, "/");
 			strcat(b, dirp->d_name);
 			if (stat(b, &sb) == -1 ||
@@ -366,10 +378,12 @@
 					     (nele + 2) * sizeof(char *));
 			if (sourcedirs == NULL)
 				abort();
-			sourcedirs[nele++] = b;
+			sourcedirs[nele++] = strdup(b);
+			free(b);
 			sourcedirs[nele] = NULL;
 		}
 		closedir(dir);
+		}
 	}
 }