diff --git a/src/main/resources/org/eolang/lints/misc/sprintf-constant-args.xsl b/src/main/resources/org/eolang/lints/misc/sprintf-constant-args.xsl
new file mode 100644
index 000000000..2b7ec10cb
--- /dev/null
+++ b/src/main/resources/org/eolang/lints/misc/sprintf-constant-args.xsl
@@ -0,0 +1,87 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+ * SPDX-FileCopyrightText: Copyright (c) 2016-2026 Objectionary.com
+ * SPDX-License-Identifier: MIT
+-->
+<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL-Transform" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:math="http://www.w3.org/2005/xpath-functions/math" xmlns:eo="https://www.eolang.org" version="2.0" id="sprintf-constant-args">
+  <xsl:import href="/org/eolang/funcs/lineno.xsl"/>
+  <xsl:import href="/org/eolang/funcs/escape.xsl"/>
+  <xsl:import href="/org/eolang/funcs/defect-context.xsl"/>
+  <xsl:output encoding="UTF-8" method="xml"/>
+  <xsl:function name="eo:hex-to-placeholder" as="xs:integer">
+    <xsl:param name="hex" as="xs:string"/>
+    <xsl:variable name="hex-upper" select="upper-case($hex)"/>
+    <xsl:variable name="length" select="string-length($hex-upper)"/>
+    <xsl:variable name="decimal" select="sum(for $i in 1 to $length return (index-of(string-to-codepoints('0123456789ABCDEF'), string-to-codepoints(substring($hex-upper, $i, 1))) - 1) * xs:integer(math:pow(16, $length - $i)))"/>
+    <xsl:sequence select="$decimal"/>
+  </xsl:function>
+  <xsl:function name="eo:count-formatters" as="xs:integer">
+    <xsl:param name="text" as="xs:string"/>
+    <xsl:variable name="txt" select="translate($text, '-', '')"/>
+    <xsl:variable name="escaped" select="replace($txt, '(25)(25)', 'ESCAPED_PERCENT')"/>
+    <xsl:variable name="strings" select="count(tokenize($escaped, '2573'))"/>
+    <xsl:variable name="numbers" select="count(tokenize($escaped, '2564'))"/>
+    <xsl:variable name="floats" select="count(tokenize($escaped, '2566'))"/>
+    <xsl:variable name="bytes" select="count(tokenize($escaped, '2578'))"/>
+    <xsl:variable name="bools" select="count(tokenize($escaped, '2562'))"/>
+    <xsl:sequence select="$strings + $numbers + $floats + $bytes + $bools - 5"/>
+  </xsl:function>
+  <xsl:function name="eo:is-constant-string" as="xs:boolean">
+    <xsl:param name="obj" as="node()"/>
+    <xsl:sequence select="
+      ($obj/@base = 'Φ.string' and $obj/o[1]/@base = 'Φ.bytes' and $obj/o[1]/o[1]/self::text())
+      or
+      ($obj/@base = 'Φ.bytes' and $obj/o[1]/self::text())
+    "/>
+  </xsl:function>
+  <xsl:template match="/">
+    <defects>
+      <xsl:for-each select="//o[@base='Φ.txt.sprintf']">
+        <xsl:variable name="text" select="o[1][@base='Φ.string']/o[1][@base='Φ.bytes']/o/text()"/>
+        <xsl:variable name="formatters" select="eo:count-formatters($text)"/>
+        <!-- Only check if format string has formatters -->
+        <xsl:if test="$formatters > 0">
+          <!-- Get the arguments (skip first child which is format string) -->
+          <xsl:variable name="args" select="o[position() > 1]"/>
+          <xsl:variable name="arg-count" select="count($args)"/>
+          <!-- Check if all arguments are constant strings -->
+          <xsl:variable name="all-constant">
+            <xsl:for-each select="$args">
+              <xsl:if test="not(eo:is-constant-string(.))">
+                <xsl:sequence select="false()"/>
+              </xsl:if>
+            </xsl:for-each>
+            <xsl:if test="$arg-count = 0">
+              <xsl:sequence select="false()"/>
+            </xsl:if>
+          </xsl:variable>
+          <!-- If format has formatters AND all args are constants, warn -->
+          <xsl:if test="$arg-count > 0 and not($args/o[1][@base!='Φ.string' or @base!='Φ.bytes'])">
+            <xsl:variable name="placeholder">
+              <xsl:for-each select="tokenize($text, '-')">
+                <xsl:value-of select="codepoints-to-string(eo:hex-to-placeholder(.))"/>
+              </xsl:for-each>
+            </xsl:variable>
+            <defect>
+              <xsl:variable name="line" select="eo:lineno(@line)"/>
+              <xsl:attribute name="line">
+                <xsl:value-of select="$line"/>
+              </xsl:attribute>
+              <xsl:if test="$line = '0'">
+                <xsl:attribute name="context">
+                  <xsl:value-of select="eo:defect-context(.)"/>
+                </xsl:attribute>
+              </xsl:if>
+              <xsl:attribute name="severity">
+                <xsl:text>warning</xsl:text>
+              </xsl:attribute>
+              <xsl:text>The \"Φ.txt.sprintf\" object uses formatters (\"%s\", \"%d\", etc.) but all arguments are constant strings – consider using a literal string instead of \"</xsl:text>
+              <xsl:value-of select="$placeholder"/>
+              <xsl:text>\"</xsl:text>
+            </defect>
+          </xsl:if>
+        </xsl:if>
+      </xsl:for-each>
+    </defects>
+  </xsl:template>
+</xsl:stylesheet>
diff --git a/src/test/resources/org/eolang/lints/packs/single/sprintf-constant-args/catches-constant-args.yaml b/src/test/resources/org/eolang/lints/packs/single/sprintf-constant-args/catches-constant-args.yaml
new file mode 100644
index 000000000..390b13358
--- /dev/null
+++ b/src/test/resources/org/eolang/lints/packs/single/sprintf-constant-args/catches-constant-args.yaml
@@ -0,0 +1,32 @@
+# SPDX-FileCopyrightText: Copyright (c) 2016-2026 Objectionary.com
+# SPDX-License-Identifier: MIT
+---
+sheets:
+  - /org/eolang/lints/misc/sprintf-constant-args.xsl
+asserts:
+  - /defects[count(defect[@severity='warning'])=1]
+  - /defects/defect[1][normalize-space()='The \"Φ.txt.sprintf\" object uses formatters (\"%s\", \"%d\", etc.) but all arguments are constant strings – consider using a literal string instead of \"%s ⌒%s\"']
+document: |
+  <object author="tests">
+    <o name="app">
+      <o base="Φ.io.stdout" name="φ">
+        <o base="Φ.txt.sprintf">
+          <o base="Φ.string">
+            <o base="Φ.bytes">
+              <o>25-73-20-25-73</o>
+            </o>
+          </o>
+          <o base="Φ.string">
+            <o base="Φ.bytes">
+              <o>68-65-6C-6C-6F</o>
+            </o>
+          </o>
+          <o base="Φ.string">
+            <o base="Φ.bytes">
+              <o>77-6F-72-6C-64-21</o>
+            </o>
+          </o>
+        </o>
+      </o>
+    </o>
+  </object>
diff --git a/src/test/resources/org/eolang/lints/packs/single/sprintf-constant-args/passes-non-constant-arg.yaml b/src/test/resources/org/eolang/lints/packs/single/sprintf-constant-args/passes-non-constant-arg.yaml
new file mode 100644
index 000000000..ce4b0bd34
--- /dev/null
+++ b/src/test/resources/org/eolang/lints/packs/single/sprintf-constant-args/passes-non-constant-arg.yaml
@@ -0,0 +1,33 @@
+# SPDX-FileCopyrightText: Copyright (c) 2016-2026 Objectionary.com
+# SPDX-License-Identifier: MIT
+---
+sheets:
+  - /org/eolang/lints/misc/sprintf-constant-args.xsl
+asserts:
+  - /defects[count(defect[@severity='warning'])=0]
+document: |
+  <object author="tests">
+    <o name="app">
+      <o base="Φ.io.stdout" name="φ">
+        <o base="Φ.txt.sprintf">
+          <o base="Φ.string">
+            <o base="Φ.bytes">
+              <o>25-73-20-25-73</o>
+            </o>
+          </o>
+          <o base="hello">
+            <o base="Φ.string">
+              <o base="Φ.bytes">
+                <o>68-65-6C-6C-6F</o>
+              </o>
+            </o>
+          </o>
+          <o base="Φ.string">
+            <o base="Φ.bytes">
+              <o>77-6F-72-6C-64-21</o>
+            </o>
+          </o>
+        </o>
+      </o>
+    </o>
+  </object>