diff --git a/src/test/java/freemarker/core/CAndCnBuiltInTest.java b/src/test/java/freemarker/core/CAndCnBuiltInTest.java
index 9e73e8a..b3c8f50 100644
--- a/src/test/java/freemarker/core/CAndCnBuiltInTest.java
+++ b/src/test/java/freemarker/core/CAndCnBuiltInTest.java
@@ -107,7 +107,7 @@
                 expectedNaN = "NaN";
             } else {
                 expectedInf = "\u221E";
-                expectedNaN = "\uFFFD";
+                expectedNaN = "NaN"; // was \uFFFD before Java 11
             }
 
             assertOutput("${" + type + "Inf?" + builtInName + "}", expectedInf);
diff --git a/src/test/java/freemarker/core/DateFormatTest.java b/src/test/java/freemarker/core/DateFormatTest.java
index 3f8a81c..5324361 100644
--- a/src/test/java/freemarker/core/DateFormatTest.java
+++ b/src/test/java/freemarker/core/DateFormatTest.java
@@ -382,7 +382,7 @@
                 + "<#setting locale='en_GB_Win'>${d} "
                 + "<#setting locale='fr_FR'>${d} "
                 + "<#setting locale='hu_HU'>${d}",
-                "2015-Sep_en 2015-Sep_en_GB 2015-Sep_en_GB 2015-sept._fr_FR 2015-szept.");
+                "2015-Sep_en 2015-Sept_en_GB 2015-Sept_en_GB 2015-sept._fr_FR 2015-szept.");
     }
     
     /**
diff --git a/src/test/java/freemarker/core/NumberFormatTest.java b/src/test/java/freemarker/core/NumberFormatTest.java
index 4d4ce23..b9f9978 100644
--- a/src/test/java/freemarker/core/NumberFormatTest.java
+++ b/src/test/java/freemarker/core/NumberFormatTest.java
@@ -332,7 +332,7 @@
             boolean cBuiltInBroken = ici.intValue() < Configuration.VERSION_2_3_21.intValue();
             boolean cNumberFormatBroken = ici.intValue() < Configuration.VERSION_2_3_31.intValue();
 
-            String humanAudienceOutput = "\u221e -\u221e \ufffd";
+            String humanAudienceOutput = "\u221e -\u221e NaN"; // NaN was \uFFFD before Java 11
             String computerAudienceOutput = ici.intValue() < Configuration.VERSION_2_3_32.intValue()
                     ? "INF -INF NaN" : "Infinity -Infinity NaN";
 
diff --git a/src/test/resources/freemarker/test/templatesuite/expected/number-format.txt b/src/test/resources/freemarker/test/templatesuite/expected/number-format.txt
index 5d8237d..326bddb 100644
--- a/src/test/resources/freemarker/test/templatesuite/expected/number-format.txt
+++ b/src/test/resources/freemarker/test/templatesuite/expected/number-format.txt
@@ -18,7 +18,7 @@
  */
 1
 1
-1 234 567,89
+1 234 567,89
 1234567.886
 1,00
 1
@@ -27,4 +27,4 @@
 1
 100000.5
 100000.5
-100 000,5
\ No newline at end of file
+100 000,5
\ No newline at end of file
diff --git a/src/test/resources/freemarker/test/templatesuite/templates/number-format.ftl b/src/test/resources/freemarker/test/templatesuite/templates/number-format.ftl
index 9d4b61f..5ffaf5c 100644
--- a/src/test/resources/freemarker/test/templatesuite/templates/number-format.ftl
+++ b/src/test/resources/freemarker/test/templatesuite/templates/number-format.ftl
@@ -58,5 +58,5 @@
 <#else>
   <@assertEquals expected="\x221E" actual="INF"?number?string />
   <@assertEquals expected="-\x221E" actual="-INF"?number?string />
-  <@assertEquals expected="\xFFFD" actual="NaN"?number?string />
+  <@assertEquals expected="NaN"<#-- was \xFFFD before Java 11 --> actual="NaN"?number?string />
 </#if>
\ No newline at end of file