diff --git a/maven-embedder/src/main/java/org/apache/maven/cli/MavenCli.java b/maven-embedder/src/main/java/org/apache/maven/cli/MavenCli.java
index e0ed45c3a424..5a8bb5523dad 100644
--- a/maven-embedder/src/main/java/org/apache/maven/cli/MavenCli.java
+++ b/maven-embedder/src/main/java/org/apache/maven/cli/MavenCli.java
@@ -1453,7 +1453,8 @@ private MavenExecutionRequest populateRequest(CliRequest cliRequest, MavenExecut
         return request;
     }
 
-    int calculateDegreeOfConcurrency(String threadConfiguration) {
+    int calculateDegreeOfConcurrency(String originalThreadConfiguration) {
+        String threadConfiguration = originalThreadConfiguration.trim();
         if (threadConfiguration.endsWith("C")) {
             threadConfiguration = threadConfiguration.substring(0, threadConfiguration.length() - 1);
 
diff --git a/maven-embedder/src/test/java/org/apache/maven/cli/MavenCliTest.java b/maven-embedder/src/test/java/org/apache/maven/cli/MavenCliTest.java
index e5fd93acb078..108667ed073f 100644
--- a/maven-embedder/src/test/java/org/apache/maven/cli/MavenCliTest.java
+++ b/maven-embedder/src/test/java/org/apache/maven/cli/MavenCliTest.java
@@ -82,10 +82,18 @@ public void testCalculateDegreeOfConcurrency() {
         assertThrows(IllegalArgumentException.class, () -> cli.calculateDegreeOfConcurrency("2C2"));
         assertThrows(IllegalArgumentException.class, () -> cli.calculateDegreeOfConcurrency("CXXX"));
         assertThrows(IllegalArgumentException.class, () -> cli.calculateDegreeOfConcurrency("XXXC"));
+        assertThrows(IllegalArgumentException.class, () -> cli.calculateDegreeOfConcurrency("1c"));
+        assertThrows(IllegalArgumentException.class, () -> cli.calculateDegreeOfConcurrency(" 1c"));
+        assertThrows(IllegalArgumentException.class, () -> cli.calculateDegreeOfConcurrency("1c "));
+        assertThrows(IllegalArgumentException.class, () -> cli.calculateDegreeOfConcurrency(" 1c "));
 
         int cpus = Runtime.getRuntime().availableProcessors();
         assertEquals((int) (cpus * 2.2), cli.calculateDegreeOfConcurrency("2.2C"));
         assertEquals(1, cli.calculateDegreeOfConcurrency("0.0001C"));
+        assertEquals(1 * cpus, cli.calculateDegreeOfConcurrency(" 1C"));
+        assertEquals(1 * cpus, cli.calculateDegreeOfConcurrency(" 1C "));
+        assertEquals(1, cli.calculateDegreeOfConcurrency(" 1"));
+        assertEquals(1, cli.calculateDegreeOfConcurrency(" 1 "));
         assertThrows(IllegalArgumentException.class, () -> cli.calculateDegreeOfConcurrency("-2.2C"));
         assertThrows(IllegalArgumentException.class, () -> cli.calculateDegreeOfConcurrency("0C"));
     }