diff --git a/docs/userguide b/docs/userguide
index e8240390..a8b35f3e 100644
--- a/docs/userguide
+++ b/docs/userguide
@@ -2320,7 +2320,9 @@ If you want to resize containers/windows using your keyboard, you can use the
 *Syntax*:
 -------------------------------------------------------
 resize grow|shrink <direction> [<px> px [or <ppt> ppt]]
-resize set <width> [px | ppt] <height> [px | ppt]
+resize set [width] <width> [px | ppt]
+resize set height <height> [px | ppt]
+resize set [width] <width> [px | ppt] [height] <height> [px | ppt]
 -------------------------------------------------------
 
 Direction can either be one of +up+, +down+, +left+ or +right+. Or you can be
diff --git a/parser-specs/commands.spec b/parser-specs/commands.spec
index 106dac99..c0c32933 100644
--- a/parser-specs/commands.spec
+++ b/parser-specs/commands.spec
@@ -254,12 +254,24 @@ state RESIZE_TILING_FINAL:
       -> call cmd_resize($way, $direction, &resize_px, &resize_ppt)
 
 state RESIZE_SET:
+  'height'
+      -> RESIZE_HEIGHT_GET_NUMBER
+  'width'
+      ->
   width = number
       -> RESIZE_WIDTH
 
 state RESIZE_WIDTH:
   mode_width = 'px', 'ppt'
       ->
+  end
+      -> call cmd_resize_set(&width, $mode_width, 0, 0)
+  'height'
+      -> RESIZE_HEIGHT_GET_NUMBER
+  height = number
+      -> RESIZE_HEIGHT
+
+state RESIZE_HEIGHT_GET_NUMBER:
   height = number
       -> RESIZE_HEIGHT
 
diff --git a/src/commands.c b/src/commands.c
index 0c5b8bcb..c7b57ab3 100644
--- a/src/commands.c
+++ b/src/commands.c
@@ -644,12 +644,12 @@ void cmd_resize_set(I3_CMD, long cwidth, const char *mode_width, long cheight, c
         if ((floating_con = con_inside_floating(current->con))) {
             Con *output = con_get_output(floating_con);
             if (cwidth == 0) {
-                cwidth = output->rect.width;
+                cwidth = floating_con->rect.width;
             } else if (mode_width && strcmp(mode_width, "ppt") == 0) {
                 cwidth = output->rect.width * ((double)cwidth / 100.0);
             }
             if (cheight == 0) {
-                cheight = output->rect.height;
+                cheight = floating_con->rect.height;
             } else if (mode_height && strcmp(mode_height, "ppt") == 0) {
                 cheight = output->rect.height * ((double)cheight / 100.0);
             }
@@ -686,7 +686,7 @@ void cmd_resize_set(I3_CMD, long cwidth, const char *mode_width, long cheight, c
                 }
             }
 
-            if (cheight > 0 && mode_width && strcmp(mode_width, "ppt") == 0) {
+            if (cheight > 0 && mode_height && strcmp(mode_height, "ppt") == 0) {
                 /* get the appropriate current container (skip stacked/tabbed cons) */
                 Con *target = current->con;
                 Con *dummy;
diff --git a/testcases/t/252-floating-size.t b/testcases/t/252-floating-size.t
index 2c8edf39..5c746de9 100644
--- a/testcases/t/252-floating-size.t
+++ b/testcases/t/252-floating-size.t
@@ -26,76 +26,92 @@ workspace ws output fake-0
 EOT
 
 ################################################################################
-# Check that setting floating windows size works
+# Init variables used for all tests.
 ################################################################################
 
 my $tmp = fresh_workspace;
-
 open_floating_window;
-
 my @content = @{get_ws($tmp)->{floating_nodes}};
 is(@content, 1, 'one floating node on this ws');
-
 my $oldrect = $content[0]->{rect};
 
-cmd 'resize set 100 px 250 px';
+sub do_test {
+    my ($width, $height) = @_;
 
-@content = @{get_ws($tmp)->{floating_nodes}};
-cmp_ok($content[0]->{rect}->{x}, '==', $oldrect->{x}, 'x untouched');
-cmp_ok($content[0]->{rect}->{y}, '==', $oldrect->{y}, 'y untouched');
-cmp_ok($content[0]->{rect}->{width}, '!=', $oldrect->{width}, 'width changed');
-cmp_ok($content[0]->{rect}->{height}, '!=', $oldrect->{width}, 'height changed');
-cmp_ok($content[0]->{rect}->{width}, '==', 100, 'width changed to 100 px');
-cmp_ok($content[0]->{rect}->{height}, '==', 250, 'height changed to 250 px');
+    cmp_ok($content[0]->{rect}->{x}, '==', $oldrect->{x}, 'x unchanged');
+    cmp_ok($content[0]->{rect}->{y}, '==', $oldrect->{y}, 'y unchanged');
+
+    @content = @{get_ws($tmp)->{floating_nodes}};
+    if ($width) {
+        cmp_ok($content[0]->{rect}->{width}, '==', $width, "width changed to $width px");
+    } else {
+        cmp_ok($content[0]->{rect}->{width}, '==', $oldrect->{width}, 'width unchanged');
+    }
+    if ($height) {
+        cmp_ok($content[0]->{rect}->{height}, '==', $height, "height changed to $height px");
+    } else {
+        cmp_ok($content[0]->{rect}->{height}, '==', $oldrect->{height}, 'height unchanged');
+    }
+    $oldrect = $content[0]->{rect};
+}
+
+################################################################################
+# Check that setting floating windows size works
+################################################################################
+
+cmd 'resize set 100 px 250 px';
+do_test(100, 250);
 
 ################################################################################
 # Same but with ppt instead of px
 ################################################################################
 
-kill_all_windows;
-$tmp = 'ws';
-cmd "workspace $tmp";
-open_floating_window;
-
-@content = @{get_ws($tmp)->{floating_nodes}};
-is(@content, 1, 'one floating node on this ws');
-
-$oldrect = $content[0]->{rect};
-
 cmd 'resize set 33 ppt 20 ppt';
-my $expected_width = int(0.33 * 1333);
-my $expected_height = int(0.2 * 999);
-
-@content = @{get_ws($tmp)->{floating_nodes}};
-cmp_ok($content[0]->{rect}->{x}, '==', $oldrect->{x}, 'x untouched');
-cmp_ok($content[0]->{rect}->{y}, '==', $oldrect->{y}, 'y untouched');
-cmp_ok($content[0]->{rect}->{width}, '!=', $oldrect->{width}, 'width changed');
-cmp_ok($content[0]->{rect}->{height}, '!=', $oldrect->{width}, 'height changed');
-cmp_ok($content[0]->{rect}->{width}, '==', $expected_width, "width changed to $expected_width px");
-cmp_ok($content[0]->{rect}->{height}, '==', $expected_height, "height changed to $expected_height px");
+do_test(int(0.33 * 1333), int(0.2 * 999));
 
 ################################################################################
 # Mix ppt and px in a single resize set command
 ################################################################################
 
 cmd 'resize set 44 ppt 111 px';
-$expected_width = int(0.44 * 1333);
-$expected_height = 111;
-
-@content = @{get_ws($tmp)->{floating_nodes}};
-cmp_ok($content[0]->{rect}->{x}, '==', $oldrect->{x}, 'x untouched');
-cmp_ok($content[0]->{rect}->{y}, '==', $oldrect->{y}, 'y untouched');
-cmp_ok($content[0]->{rect}->{width}, '==', $expected_width, "width changed to $expected_width px");
-cmp_ok($content[0]->{rect}->{height}, '==', $expected_height, "height changed to $expected_height px");
+do_test(int(0.44 * 1333), 111);
 
 cmd 'resize set 222 px 100 ppt';
-$expected_width = 222;
-$expected_height = 999;
+do_test(222, 999);
 
-@content = @{get_ws($tmp)->{floating_nodes}};
-cmp_ok($content[0]->{rect}->{x}, '==', $oldrect->{x}, 'x untouched');
-cmp_ok($content[0]->{rect}->{y}, '==', $oldrect->{y}, 'y untouched');
-cmp_ok($content[0]->{rect}->{width}, '==', $expected_width, "width changed to $expected_width px");
-cmp_ok($content[0]->{rect}->{height}, '==', $expected_height, "height changed to $expected_height px");
+################################################################################
+# Zero is interpreted as no change.
+# See issue: #3276.
+################################################################################
+
+cmd 'resize set 0 px 333 px';
+do_test(0, 333);
+
+cmd 'resize set 333 px 0 ppt';
+do_test(333, 0);
+
+cmd 'resize set 0 px 0 ppt';
+do_test(0, 0);
+
+cmd 'resize set 100 ppt 0 px';
+do_test(1333, 0);
+
+################################################################################
+# Use 'width' and 'height' keywords.
+# See issue: #3275.
+################################################################################
+
+cmd 'resize set width 200 px';
+do_test(200, 0);
+
+cmd 'resize set height 200 px';
+do_test(0, 200);
+
+cmd 'resize set width 300 px height 300 px';
+do_test(300, 300);
+
+# ppt + keyword used only for height
+cmd 'resize set 100 ppt height 100 px';
+do_test(1333, 100);
 
 done_testing;
diff --git a/testcases/t/541-resize-set-tiling.t b/testcases/t/541-resize-set-tiling.t
index 82267baf..fcf3267a 100644
--- a/testcases/t/541-resize-set-tiling.t
+++ b/testcases/t/541-resize-set-tiling.t
@@ -39,6 +39,14 @@ my ($nodes, $focus) = get_ws_content($tmp);
 cmp_float($nodes->[0]->{percent}, 0.25, 'left window got only 25%');
 cmp_float($nodes->[1]->{percent}, 0.75, 'right window got 75%');
 
+# Same but use the 'width' keyword.
+cmd 'resize set width 80 ppt';
+
+($nodes, $focus) = get_ws_content($tmp);
+
+cmp_float($nodes->[0]->{percent}, 0.20, 'left window got 20%');
+cmp_float($nodes->[1]->{percent}, 0.80, 'right window got 80%');
+
 ############################################################
 # resize vertically
 ############################################################
@@ -61,6 +69,13 @@ my ($nodes, $focus) = get_ws_content($tmp);
 cmp_float($nodes->[0]->{percent}, 0.25, 'top window got only 25%');
 cmp_float($nodes->[1]->{percent}, 0.75, 'bottom window got 75%');
 
+# Same but use the 'height' keyword.
+cmd 'resize set height 80 ppt';
+
+($nodes, $focus) = get_ws_content($tmp);
+
+cmp_float($nodes->[0]->{percent}, 0.20, 'top window got 20%');
+cmp_float($nodes->[1]->{percent}, 0.80, 'bottom window got 80%');
 
 ############################################################
 # resize horizontally and vertically