diff --git a/test/gc/g1/TestHumongousShrinkHeap.java b/test/gc/g1/TestHumongousShrinkHeap.java
index 97d60546b2546e9c330aa12d2c943aff48cccc2f..b350bcd8611e985f0921eae41d8ea3f025bdf7d4 100644
--- a/test/gc/g1/TestHumongousShrinkHeap.java
+++ b/test/gc/g1/TestHumongousShrinkHeap.java
@@ -24,9 +24,12 @@
 /**
  * @test TestHumongousShrinkHeap
  * @bug 8036025 8056043
- * @summary Verify that heap shrinks after GC in the presence of fragmentation due to humongous objects
+ * @summary Verify that heap shrinks after GC in the presence of fragmentation
+ * due to humongous objects
  * @library /testlibrary
- * @run main/othervm -XX:MinHeapFreeRatio=10 -XX:MaxHeapFreeRatio=12 -XX:+UseG1GC -XX:G1HeapRegionSize=1M -verbose:gc TestHumongousShrinkHeap
+ * @run main/othervm -XX:-ExplicitGCInvokesConcurrent -XX:MinHeapFreeRatio=10
+ * -XX:MaxHeapFreeRatio=12 -XX:+UseG1GC -XX:G1HeapRegionSize=1M -verbose:gc
+ * TestHumongousShrinkHeap
  */
 
 import java.lang.management.ManagementFactory;
diff --git a/test/gc/g1/TestShrinkAuxiliaryData.java b/test/gc/g1/TestShrinkAuxiliaryData.java
index a185fe5d4e83844aa8be2d53aecdb69f46916f51..cba813882a51a9d7d721f28f63ec7ec9958ed49f 100644
--- a/test/gc/g1/TestShrinkAuxiliaryData.java
+++ b/test/gc/g1/TestShrinkAuxiliaryData.java
@@ -45,6 +45,7 @@ public class TestShrinkAuxiliaryData {
         "-XX:MaxHeapFreeRatio=11",
         "-XX:+UseG1GC",
         "-XX:G1HeapRegionSize=1m",
+        "-XX:-ExplicitGCInvokesConcurrent",
         "-XX:+PrintGCDetails"
     };
 
diff --git a/test/gc/g1/TestShrinkDefragmentedHeap.java b/test/gc/g1/TestShrinkDefragmentedHeap.java
index 94eb690e97d3fa95475aadc03540ed2f507b5a11..c23c8721af35d721ee6cd5d1f1f415dab12be492 100644
--- a/test/gc/g1/TestShrinkDefragmentedHeap.java
+++ b/test/gc/g1/TestShrinkDefragmentedHeap.java
@@ -59,6 +59,7 @@ public class TestShrinkDefragmentedHeap {
                 "-XX:MaxHeapFreeRatio=11",
                 "-XX:+UseG1GC",
                 "-XX:G1HeapRegionSize=" + REGION_SIZE,
+                "-XX:-ExplicitGCInvokesConcurrent",
                 "-verbose:gc",
                 GCTest.class.getName()
         );