diff --git a/classlib/src/main/java/org/teavm/classlib/java/lang/TSystem.java b/classlib/src/main/java/org/teavm/classlib/java/lang/TSystem.java
index 820140a30..beb54c301 100644
--- a/classlib/src/main/java/org/teavm/classlib/java/lang/TSystem.java
+++ b/classlib/src/main/java/org/teavm/classlib/java/lang/TSystem.java
@@ -28,6 +28,7 @@ import org.teavm.interop.DelegateTo;
 import org.teavm.interop.Import;
 import org.teavm.interop.NoSideEffects;
 import org.teavm.interop.Unmanaged;
+import org.teavm.jso.browser.Performance;
 import org.teavm.runtime.Allocator;
 import org.teavm.runtime.GC;
 import org.teavm.runtime.RuntimeArray;
@@ -222,9 +223,16 @@ public final class TSystem extends TObject {
     }
 
     public static long nanoTime() {
-        return currentTimeMillis() * 1000000;
+        if (PlatformDetector.isLowLevel()) {
+            return nanoTimeLowLevel();
+        } else {
+            return (long) (Performance.now() * 1000000);
+        }
     }
 
+    @Import(name = "currentTimeNano")
+    private static native long nanoTimeLowLevel();
+
     public static int identityHashCode(Object x) {
         return ((TObject) x).identity();
     }
diff --git a/core/src/main/resources/org/teavm/backend/c/runtime.c b/core/src/main/resources/org/teavm/backend/c/runtime.c
index db0e9606e..a4b9295d5 100644
--- a/core/src/main/resources/org/teavm/backend/c/runtime.c
+++ b/core/src/main/resources/org/teavm/backend/c/runtime.c
@@ -232,7 +232,13 @@ static int64_t currentTimeMillis() {
     struct timespec time;
     clock_gettime(CLOCK_REALTIME, &time);
 
-    return time.tv_sec * 1000 + (int64_t) round(time.tv_nsec / 1000000);
+    return time.tv_sec * INT64_C(1000) + (int64_t) round(time.tv_nsec / 1000000);
+}
+static int64_t currentTimeNano() {
+    struct timespec time;
+    clock_gettime(CLOCK_REALTIME, &time);
+
+    return time.tv_sec * INT64_C(1000000000) + (int64_t) round(time.tv_nsec);
 }
 #endif