diff --git a/src/hotspot/share/runtime/globals.hpp b/src/hotspot/share/runtime/globals.hpp
index 0618a3eb006..41736c91bc3 100644
--- a/src/hotspot/share/runtime/globals.hpp
+++ b/src/hotspot/share/runtime/globals.hpp
@@ -1292,9 +1292,10 @@ const int ObjectAlignmentInBytes = 8;
           "(0 means none)")                                                 \
           range(0, max_jint)                                                \
                                                                             \
-  product(intx, SafepointTimeoutDelay, 10000,                               \
-          "Delay in milliseconds for option SafepointTimeout")              \
-          range(0, max_intx LP64_ONLY(/MICROUNITS))                         \
+  product(double, SafepointTimeoutDelay, 10000,                             \
+          "Delay in milliseconds for option SafepointTimeout; "             \
+          "supports sub-millisecond resolution with fractional values.")    \
+          range(0, max_jlongDouble LP64_ONLY(/MICROUNITS))                  \
                                                                             \
   product(bool, UseSystemMemoryBarrier, false,                              \
           "Try to enable system memory barrier if supported by OS")         \
diff --git a/src/hotspot/share/runtime/safepoint.cpp b/src/hotspot/share/runtime/safepoint.cpp
index 1d0997914c5..b2bdf22298b 100644
--- a/src/hotspot/share/runtime/safepoint.cpp
+++ b/src/hotspot/share/runtime/safepoint.cpp
@@ -379,7 +379,7 @@ void SafepointSynchronize::begin() {
   if (SafepointTimeout) {
     // Set the limit time, so that it can be compared to see if this has taken
     // too long to complete.
-    safepoint_limit_time = SafepointTracing::start_of_safepoint() + (jlong)SafepointTimeoutDelay * (NANOUNITS / MILLIUNITS);
+    safepoint_limit_time = SafepointTracing::start_of_safepoint() + (jlong)(SafepointTimeoutDelay * NANOSECS_PER_MILLISEC);
     timeout_error_printed = false;
   }
 
@@ -819,7 +819,7 @@ void SafepointSynchronize::print_safepoint_timeout() {
         os::naked_sleep(3000);
       }
     }
-    fatal("Safepoint sync time longer than " INTX_FORMAT "ms detected when executing %s.",
+    fatal("Safepoint sync time longer than %.6f ms detected when executing %s.",
           SafepointTimeoutDelay, VMThread::vm_operation()->name());
   }
 }
diff --git a/test/hotspot/jtreg/runtime/CommandLine/DoubleFlagWithIntegerValue.java b/test/hotspot/jtreg/runtime/CommandLine/DoubleFlagWithIntegerValue.java
index f26b7399671..861160ee787 100644
--- a/test/hotspot/jtreg/runtime/CommandLine/DoubleFlagWithIntegerValue.java
+++ b/test/hotspot/jtreg/runtime/CommandLine/DoubleFlagWithIntegerValue.java
@@ -35,18 +35,24 @@ import jdk.test.lib.process.ProcessTools;
 import jdk.test.lib.process.OutputAnalyzer;
 
 public class DoubleFlagWithIntegerValue {
-  public static void testDoubleFlagWithValue(String value) throws Exception {
-    ProcessBuilder pb = ProcessTools.createJavaProcessBuilder("-XX:SweeperThreshold=" + value, "-version");
+  public static void testDoubleFlagWithValue(String flag, String value) throws Exception {
+    ProcessBuilder pb = ProcessTools.createJavaProcessBuilder(flag + "=" + value, "-version");
     OutputAnalyzer output = new OutputAnalyzer(pb.start());
     output.shouldNotContain("Improperly specified VM option");
     output.shouldHaveExitValue(0);
   }
 
   public static void main(String[] args) throws Exception {
-    // Test double format
-    testDoubleFlagWithValue("10.0");
+    // Test double format for -XX:SweeperThreshold
+    testDoubleFlagWithValue("-XX:SweeperThreshold", "10.0");
 
-    // Test integer format
-    testDoubleFlagWithValue("10");
+    // Test integer format -XX:SweeperThreshold
+    testDoubleFlagWithValue("-XX:SweeperThreshold", "10");
+
+    // Test double format for -XX:SafepointTimeoutDelay
+    testDoubleFlagWithValue("-XX:SafepointTimeoutDelay", "5.0");
+
+    // Test integer format -XX:SafepointTimeoutDelay
+    testDoubleFlagWithValue("-XX:SafepointTimeoutDelay", "5");
   }
 }