diff --git a/app/src/main/java/com/httrack/android/OptionValues.java b/app/src/main/java/com/httrack/android/OptionValues.java
index d56d525..76bfee1 100644
--- a/app/src/main/java/com/httrack/android/OptionValues.java
+++ b/app/src/main/java/com/httrack/android/OptionValues.java
@@ -21,6 +21,7 @@
 
 package com.httrack.android;
 
+import java.math.BigDecimal;
 import java.nio.charset.StandardCharsets;
 import java.util.regex.Pattern;
 
@@ -103,6 +104,29 @@ public static boolean isAtMost(final String value, final long max) {
     }
   }
 
+  /** Lowest non-zero rate the engine takes for -%c, and the highest. */
+  private static final String MIN_RATE = "0.000001";
+
+  private static final String MAX_RATE = new BigDecimal(Float.MAX_VALUE)
+      .toPlainString();
+
+  /**
+   * The rate brought inside the range the engine accepts. The engine panics on
+   * a rate between zero and 0.000001 or above a float, and a zero means no
+   * limit, so it stays.
+   *
+   * @param value
+   *          A value isDecimal accepted
+   * @return the value, or the nearest rate the engine takes
+   */
+  public static String clampRate(final String value) {
+    final double rate = Double.parseDouble(value);
+    if (rate > 0 && rate < Double.parseDouble(MIN_RATE)) {
+      return MIN_RATE;
+    }
+    return rate > Float.MAX_VALUE ? MAX_RATE : value;
+  }
+
   /**
    * True if the value is at most max bytes of UTF-8. An engine buffer is a byte
    * count, so a limit measured in characters lets a non-ASCII value through.
diff --git a/app/src/main/java/com/httrack/android/OptionsMapper.java b/app/src/main/java/com/httrack/android/OptionsMapper.java
index 4d6e5c5..002df20 100755
--- a/app/src/main/java/com/httrack/android/OptionsMapper.java
+++ b/app/src/main/java/com/httrack/android/OptionsMapper.java
@@ -1736,9 +1736,12 @@ public void emit(final List<String> commandline, final String value) {
        * as a URL, which turns -r1.5 into an exclusion filter. */
       /* Over the cap the engine refuses the command line or misreads the
        * value, and no layout bounds these fields. */
+      /* A rate the engine refuses is clamped, because dropping it would leave
+       * the crawl with no rate limit at all. */
       if (fraction ? OptionValues.isDecimal(value) : OptionValues.isAtMost(
           value, max)) {
-        commandline.add("-" + option + value);
+        commandline.add(
+            "-" + option + (fraction ? OptionValues.clampRate(value) : value));
       } else {
         refused(commandline, value);
       }
diff --git a/app/src/main/jni/Android.mk b/app/src/main/jni/Android.mk
index 8bd1a6d..e49247f 100755
--- a/app/src/main/jni/Android.mk
+++ b/app/src/main/jni/Android.mk
@@ -74,6 +74,7 @@ LOCAL_SRC_FILES := httrack/src/htscore.c httrack/src/htsparse.c 			\
 	httrack/src/htstools.c httrack/src/htswizard.c httrack/src/htsalias.c 	\
 	httrack/src/htsthread.c httrack/src/htsindex.c httrack/src/htsbauth.c 	\
 	httrack/src/htsbundle.c									\
+	httrack/src/htsbase.c									\
 	httrack/src/htsmd5.c httrack/src/htszlib.c httrack/src/htswrap.c 		\
 	httrack/src/htsconcat.c httrack/src/htsmodules.c 						\
 	httrack/src/htscharset.c httrack/src/punycode.c 						\
@@ -113,6 +114,8 @@ LOCAL_CFLAGS += -O3 -g3 -funwind-tables -fPIC 					\
 	-Wno-nested-externs														\
 	-D_REENTRANT -DPIC -DANDROID -D_ANDROID -DHAVE_CONFIG_H -DINET6 -DHTS_INTERNAL_BUILD			\
 	-DLIBHTTRACK_EXPORTS -DZLIB_CONST -DHTS_INTHASH_USES_MD5 -DLIBICONV_PLUG
+# HTS_INTERNAL_BYTECODE shows the engine-only half of the headers to the library.
+LOCAL_CFLAGS += -DHTS_INTERNAL_BYTECODE
 # The app never asks the engine for a self-test. The sources are gone from
 # LOCAL_SRC_FILES above too, because htsselftest_int.h #errors under this macro.
 LOCAL_CFLAGS += -DHTS_NO_SELFTEST
diff --git a/app/src/main/jni/httrack b/app/src/main/jni/httrack
index 483d5d4..7a923f4 160000
--- a/app/src/main/jni/httrack
+++ b/app/src/main/jni/httrack
@@ -1 +1 @@
-Subproject commit 483d5d47a6243cf57d1495e473a09a09519f3dea
+Subproject commit 7a923f4047df1bec18e2ce1b4403c7038d055021
diff --git a/app/src/test/java/com/httrack/android/NumericOptionValueTest.java b/app/src/test/java/com/httrack/android/NumericOptionValueTest.java
index 63598f4..580b04c 100644
--- a/app/src/test/java/com/httrack/android/NumericOptionValueTest.java
+++ b/app/src/test/java/com/httrack/android/NumericOptionValueTest.java
@@ -141,6 +141,51 @@ public void aSizeTheEngineWouldPanicOnNeverReachesIt() {
     }
   }
 
+  /** The float option's own bounds, which the pinned engine enforces. */
+  private static final String MIN_RATE = "0.000001";
+
+  private static final String MAX_RATE =
+      "340282346638528859811704183484516925440";
+
+  /* The engine panics on a rate between zero and the floor, and on one above a
+     float, where it used to cast whatever it read. */
+  @Test
+  public void aRateTheEngineWouldPanicOnIsClampedToTheBound() {
+    final OptionMapper mapper = new SimpleOption(FLOAT_OPTION, true);
+    for (final String value : new String[] { "0.0000001", "0.0000000001",
+        "0.00000099" }) {
+      assertEquals("-" + FLOAT_OPTION + MIN_RATE, emit(mapper, value).get(0));
+    }
+    assertEquals("-" + FLOAT_OPTION + MAX_RATE,
+        emit(mapper, "99999999999999999999999999999999999999999").get(0));
+  }
+
+  /** A zero means no limit and the engine still takes it. */
+  @Test
+  public void aRateTheEngineTakesIsSentUnchanged() {
+    final OptionMapper mapper = new SimpleOption(FLOAT_OPTION, true);
+    for (final String value : new String[] { "0", "0.0", MIN_RATE, "0.5", "5.0",
+        "100" }) {
+      assertEquals("-" + FLOAT_OPTION + value, emit(mapper, value).get(0));
+    }
+  }
+
+  /* The bounds live in the engine, so read them back: a moved floor must fail
+     here rather than ship a rate the engine panics on. */
+  @Test
+  public void theClampedBoundsAreTheOnesTheEngineChecks() throws IOException {
+    final String main = TestSources
+        .read(TestSources.engineFile("src/htscoremain.c"));
+    final String gate = TestSources.balancedBlock(main,
+        TestSources.indexOf(main, "case 'c': {"));
+    assertTrue("the engine no longer bounds -" + FLOAT_OPTION + " at 1e-6",
+        gate.contains("v >= 1e-6f"));
+    assertTrue("the engine no longer bounds -" + FLOAT_OPTION + " at FLT_MAX",
+        gate.contains("v <= FLT_MAX"));
+    assertEquals(1e-6, Double.parseDouble(MIN_RATE), 0.0);
+    assertEquals(Float.MAX_VALUE, Double.parseDouble(MAX_RATE), 0.0);
+  }
+
   @Test
   public void isPositiveRejectsWhatIsDigitsAccepts() {
     assertTrue(OptionValues.isDigits("0"));