diff --git a/include/data.h b/include/data.h
index f6dc0d7c..47bf4ac0 100644
--- a/include/data.h
+++ b/include/data.h
@@ -158,7 +158,7 @@ struct deco_render_params {
 };
 
 /**
- * Stores which workspace (by name) goes to which output.
+ * Stores which workspace (by name or number) goes to which output.
  *
  */
 struct Workspace_Assignment {
diff --git a/include/util.h b/include/util.h
index 53ea68e4..ac21b870 100644
--- a/include/util.h
+++ b/include/util.h
@@ -58,6 +58,19 @@ int max(int a, int b);
 bool rect_contains(Rect rect, uint32_t x, uint32_t y);
 Rect rect_add(Rect a, Rect b);
 
+/**
+ * Returns true if the name consists of only digits.
+ *
+ */
+__attribute__((pure)) bool name_is_digits(const char *name);
+
+/**
+ * Parses the workspace name as a number. Returns -1 if the workspace should be
+ * interpreted as a "named workspace".
+ *
+ */
+long ws_name_to_number(const char *name);
+
 /**
  * Updates *destination with new_value and returns true if it was changed or false
  * if it was the same
diff --git a/src/util.c b/src/util.c
index c3336e15..5db30c9d 100644
--- a/src/util.c
+++ b/src/util.c
@@ -21,6 +21,7 @@
 #include <pwd.h>
 #include <yajl/yajl_version.h>
 #include <libgen.h>
+#include <ctype.h>
 
 #define SN_API_NOT_YET_FROZEN 1
 #include <libsn/sn-launcher.h>
@@ -47,6 +48,38 @@ Rect rect_add(Rect a, Rect b) {
                   a.height + b.height};
 }
 
+/*
+ * Returns true if the name consists of only digits.
+ *
+ */
+__attribute__ ((pure)) bool name_is_digits(const char *name) {
+    /* positive integers and zero are interpreted as numbers */
+    for (int i = 0; i < strlen(name); i++)
+        if (!isdigit(name[i]))
+            return false;
+
+    return true;
+}
+
+/*
+ * Parses the workspace name as a number. Returns -1 if the workspace should be
+ * interpreted as a "named workspace".
+ *
+ */
+long ws_name_to_number(const char *name) {
+    /* positive integers and zero are interpreted as numbers */
+    char *endptr = NULL;
+    long parsed_num = strtol(name, &endptr, 10);
+    if (parsed_num == LONG_MIN ||
+            parsed_num == LONG_MAX ||
+            parsed_num < 0 ||
+            endptr == name) {
+        parsed_num = -1;
+    }
+
+    return parsed_num;
+}
+
 /*
  * Updates *destination with new_value and returns true if it was changed or false
  * if it was the same
diff --git a/src/workspace.c b/src/workspace.c
index 99c2166a..256b0804 100644
--- a/src/workspace.c
+++ b/src/workspace.c
@@ -53,14 +53,25 @@ Con *workspace_get(const char *num, bool *created) {
         output = con_get_output(focused);
         /* look for assignments */
         struct Workspace_Assignment *assignment;
-        TAILQ_FOREACH(assignment, &ws_assignments, ws_assignments) {
-            if (strcmp(assignment->name, num) != 0)
-                continue;
 
-            LOG("Found workspace assignment to output \"%s\"\n", assignment->output);
-            GREP_FIRST(output, croot, !strcmp(child->name, assignment->output));
-            break;
+        /* We set workspace->num to the number if this workspace’s name begins
+         * with a positive number. Otherwise it’s a named ws and num will be
+         * -1. */
+        long parsed_num = ws_name_to_number(num);
+
+        TAILQ_FOREACH(assignment, &ws_assignments, ws_assignments) {
+            if (strcmp(assignment->name, num) == 0) {
+                DLOG("Found workspace name assignment to output \"%s\"\n", assignment->output);
+                GREP_FIRST(output, croot, !strcmp(child->name, assignment->output));
+                break;
+            } else if (parsed_num != -1
+                    && name_is_digits(assignment->name)
+                    && ws_name_to_number(assignment->name) == parsed_num) {
+                DLOG("Found workspace number assignment to output \"%s\"\n", assignment->output);
+                GREP_FIRST(output, croot, !strcmp(child->name, assignment->output));
+            }
         }
+
         Con *content = output_get_content(output);
         LOG("got output %p with content %p\n", output, content);
         /* We need to attach this container after setting its type. con_attach
@@ -74,16 +85,7 @@ Con *workspace_get(const char *num, bool *created) {
         FREE(workspace->name);
         workspace->name = sstrdup(num);
         workspace->workspace_layout = config.default_layout;
-        /* We set ->num to the number if this workspace’s name begins with a
-         * positive number. Otherwise it’s a named ws and num will be -1. */
-        char *endptr = NULL;
-        long parsed_num = strtol(num, &endptr, 10);
-        if (parsed_num == LONG_MIN ||
-            parsed_num == LONG_MAX ||
-            parsed_num < 0 ||
-            endptr == num)
-            workspace->num = -1;
-        else workspace->num = parsed_num;
+        workspace->num = parsed_num;
         LOG("num = %d\n", workspace->num);
 
         workspace->parent = content;
diff --git a/testcases/t/518-interpret-workspace-numbers.t b/testcases/t/518-interpret-workspace-numbers.t
new file mode 100644
index 00000000..577881f0
--- /dev/null
+++ b/testcases/t/518-interpret-workspace-numbers.t
@@ -0,0 +1,77 @@
+#!perl
+# vim:ts=4:sw=4:expandtab
+#
+# Please read the following documents before working on tests:
+# • http://build.i3wm.org/docs/testsuite.html
+#   (or docs/testsuite)
+#
+# • http://build.i3wm.org/docs/lib-i3test.html
+#   (alternatively: perldoc ./testcases/lib/i3test.pm)
+#
+# • http://build.i3wm.org/docs/ipc.html
+#   (or docs/ipc)
+#
+# • http://onyxneon.com/books/modern_perl/modern_perl_a4.pdf
+#   (unless you are already familiar with Perl)
+#
+# Tests that workspace assignment config directives for plain numbers will
+# assign any workspace of that number to the specified output.
+# Ticket: #1238
+# Bug still in: 4.7.2-147-g3760a48
+use i3test i3_autostart => 0;
+
+my $config = <<EOT;
+# i3 config file (v4)
+font -misc-fixed-medium-r-normal--13-120-75-75-C-70-iso10646-1
+
+workspace 1:override output fake-0
+workspace 2 output fake-0
+workspace 1 output fake-1
+workspace 2:override output fake-1
+
+fake-outputs 1024x768+0+0,1024x768+1024+0
+EOT
+
+my $pid = launch_with_config($config);
+my $i3 = i3(get_socket_path());
+$i3->connect->recv;
+
+# Returns the name of the output on which this workspace resides
+sub get_output_for_workspace {
+    my $ws_name = shift @_;
+
+    foreach (grep { not $_->{name} =~ /^__/ } @{$i3->get_tree->recv->{nodes}}) {
+        my $output = $_->{name};
+        foreach (grep { $_->{name} =~ "content" } @{$_->{nodes}}) {
+            return $output if $_->{nodes}[0]->{name} =~ $ws_name;
+        }
+    }
+}
+
+################################################################################
+# Workspace assignments with bare numbers should be interpreted as `workspace
+# number` config directives. Any workspace beginning with that number should be
+# assigned to the specified output.
+################################################################################
+
+cmd 'focus output fake-1';
+cmd 'workspace "2:foo"';
+is(get_output_for_workspace('2:foo'), 'fake-0',
+    'Workspaces should be assigned by number when the assignment is a plain number')
+    or diag 'Since workspace number 2 is assigned to fake-0, 2:foo should open on fake-0';
+
+cmd 'focus output fake-0';
+cmd 'workspace "2:override"';
+is(get_output_for_workspace('2:override'), 'fake-1',
+    'Workspace assignments by name should override numbered assignments')
+    or diag 'Since workspace "2:override" is assigned by name to fake-1, it should open on fake-1';
+
+cmd 'focus output fake-1';
+cmd 'workspace "1:override"';
+is(get_output_for_workspace('1:override'), 'fake-0',
+    'Assignment rules should not be affected by the order assignments are declared')
+    or diag 'Since workspace "1:override" is assigned by name to fake-0, it should open on fake-0';
+
+exit_gracefully($pid);
+
+done_testing;