diff --git a/ps.deploy.ts b/ps.deploy.ts
index 5a1074cf..e2d468f9 100644
--- a/ps.deploy.ts
+++ b/ps.deploy.ts
@@ -4,7 +4,7 @@ import * as spritedata from '@smogon/sprite-data/index.ts';
 import {gen10Modelslike, gen5Gifs} from './rules/modelslike.ts';
 import {type Sprite, toPSID} from './rules/publish.ts';
 import {forEachRule, memo, rule} from './tools/build/artifact.ts';
-import {base, compresspng, pad, spriteglob} from './tools/build/helpers.ts';
+import {PNG_DETERMINISTIC, base, compresspng, pad, spriteglob} from './tools/build/helpers.ts';
 import {type DeployCtx, defineDeploy} from './tools/deploy/api.ts';
 
 // PS spritesheets. The sheet tools readdir the minisprite dirs and resolve
@@ -49,7 +49,7 @@ rule([
 ], {
     display: "pokemonicons-pokeball-sheet",
     cmds: [
-        "magick convert -background transparent -gravity center -extent 40x30 %f +append %o",
+        `magick convert ${PNG_DETERMINISTIC} -background transparent -gravity center -extent 40x30 %f +append %o`,
         compresspng({config: "SPRITESHEET"}),
     ],
 }, ["pokemonicons-pokeball-sheet.png"]);
@@ -74,8 +74,8 @@ const paddedDex = memo(() => {
     return dex.concat(forEachRule(dexMissing, {
         display: "missing dex %B",
         cmds: [
-            'magick convert "%f[0]" -trim %o',
-            'magick mogrify -background transparent -gravity center -resize "120x120>" -extent 120x120 %o',
+            `magick convert "%f[0]" ${PNG_DETERMINISTIC} -trim %o`,
+            `magick mogrify ${PNG_DETERMINISTIC} -background transparent -gravity center -resize "120x120>" -extent 120x120 %o`,
             compresspng({config: "DEX"}),
         ],
     }, "%B.png"));
diff --git a/rules/social.ts b/rules/social.ts
index c52889c2..c3fd5cd3 100644
--- a/rules/social.ts
+++ b/rules/social.ts
@@ -1,6 +1,6 @@
 
 import {forEachRule, memo} from '../tools/build/artifact.ts';
-import {base, compresspng, spriteglob} from '../tools/build/helpers.ts';
+import {PNG_DETERMINISTIC, base, compresspng, spriteglob} from '../tools/build/helpers.ts';
 
 // Smogdex social images: models, backfilled with gen9 species not yet in
 // models (first source wins).
@@ -20,7 +20,7 @@ const socialInputs = memo(() => {
 export const fbSprites = memo(() => forEachRule(socialInputs(), {
     display: "fbsprite %f",
     cmds: [
-        'magick convert "%f[0]" -trim -resize 150x150 -background white -gravity center -extent 198x198 -bordercolor black -border 1 %o',
+        `magick convert "%f[0]" ${PNG_DETERMINISTIC} -trim -resize 150x150 -background white -gravity center -extent 198x198 -bordercolor black -border 1 %o`,
         compresspng({config: "MODELS"}),
     ],
 }, "%B.png"));
@@ -28,7 +28,7 @@ export const fbSprites = memo(() => forEachRule(socialInputs(), {
 export const twitterSprites = memo(() => forEachRule(socialInputs(), {
     display: "twittersprite %f",
     cmds: [
-        'magick convert "%f[0]" -trim -resize 115x115 -background white -gravity center -extent 120x120 %o',
+        `magick convert "%f[0]" ${PNG_DETERMINISTIC} -trim -resize 115x115 -background white -gravity center -extent 120x120 %o`,
         compresspng({config: "MODELS"}),
     ],
 }, "%B.png"));
diff --git a/tools/build/helpers.ts b/tools/build/helpers.ts
index 493f5fff..6bc6d0f0 100644
--- a/tools/build/helpers.ts
+++ b/tools/build/helpers.ts
@@ -97,14 +97,18 @@ export function spriteglob(pats : string | string[], flagspec? : Record<string,
     });
 }
 
+// PNG date/time tEXt chunks make magick output nondeterministic, which would
+// churn every content-addressed name on a rebuild.
+export const PNG_DETERMINISTIC = '-define png:exclude-chunks=date,time';
+
 export function pad(opts : {w : number, h : number, input? : string, output? : string}) : string {
     const input = opts.input ?? '%f';
     const output = opts.output ?? '%o';
-    return `magick convert ${input} -background transparent -gravity center -extent ${opts.w}x${opts.h} ${output}`;
+    return `magick convert ${input} ${PNG_DETERMINISTIC} -background transparent -gravity center -extent ${opts.w}x${opts.h} ${output}`;
 }
 
 export function trimimg(opts : {input? : string, output? : string} = {}) : string {
-    return `magick convert ${opts.input ?? '%f'} -trim ${opts.output ?? '%o'}`;
+    return `magick convert ${opts.input ?? '%f'} ${PNG_DETERMINISTIC} -trim ${opts.output ?? '%o'}`;
 }
 
 interface CompressOpts {
diff --git a/tools/sheet/index.ts b/tools/sheet/index.ts
index ec53e7dc..a37a605e 100644
--- a/tools/sheet/index.ts
+++ b/tools/sheet/index.ts
@@ -28,6 +28,8 @@ for (let i = 0; i < sheet.entries.length; i++) {
 const proc = cp.spawn("magick", [
     "montage",
     "@-",
+    // Keep sheet bytes deterministic for the content-addressed build.
+    "-define", "png:exclude-chunks=date,time",
     "-background", "transparent",
     "-geometry", `${sheet.width}x${sheet.height}>`,
     "-gravity", "center",