diff --git a/Rules/Languages/de/SharedRules/general.yaml b/Rules/Languages/de/SharedRules/general.yaml
index 4c0f252fb..3098d76ac 100644
--- a/Rules/Languages/de/SharedRules/general.yaml
+++ b/Rules/Languages/de/SharedRules/general.yaml
@@ -460,9 +460,9 @@
       else: [T: "kovarianz"]      # phrase('covariance' function)
 
 -
-  name: log    # handle both log and ln (if in an mrow, 'intents' are used)
+  name: log    # handle log, principal Log, and ln (if in an mrow, 'intents' are used)
   tag: mi
-  match: ".='log' or .='ln'"
+  match: ".='log' or .='Log' or .='ln'"
   replace:
   - bookmark: "@id"
   - test:
@@ -472,6 +472,8 @@
   - test:
     - if: ".= 'log'"
       then: [T: "log"]      # phrase(the 'log' function is used in mathematics)
+    - else_if: ".= 'Log'"
+      then: [T: "hauptwert des logarithmus"]
     - else_if: "$Verbosity='Terse'"
       then: [spell: "'ln'"]
       else: [T: "natürliche logarithmus"]      # phrase(the 'natural log' function is used in mathematics)
diff --git a/tests/Languages/de/ClearSpeak/functions.rs b/tests/Languages/de/ClearSpeak/functions.rs
index 6cb30e259..90217658e 100644
--- a/tests/Languages/de/ClearSpeak/functions.rs
+++ b/tests/Languages/de/ClearSpeak/functions.rs
@@ -106,6 +106,15 @@ fn simple_log() -> Result<()> {
 
 }
 
+#[test]
+fn principal_value_log() -> Result<()> {
+    // Uppercase Log denotes the principal-value logarithm.
+    let expr = "<math><mrow><mi>Log</mi><mi>x</mi></mrow></math>";
+    test("de", "ClearSpeak", expr, "der hauptwert des logarithmus, von x")?;
+    test("de", "SimpleSpeak", expr, "der hauptwert des logarithmus, von x")?;
+    Ok(())
+}
+
 #[test]
 fn normal_log() -> Result<()> {
     let expr = "<math><mrow><mi>log</mi><mrow><mo>(</mo><mrow><mi>x</mi><mo>+</mo><mi>y</mi></mrow><mo>)</mo></mrow></mrow></math>";