diff --git a/mysql-test/main/type_float.result b/mysql-test/main/type_float.result
index a3fa3d435d511..22ef549cd6168 100644
--- a/mysql-test/main/type_float.result
+++ b/mysql-test/main/type_float.result
@@ -154,6 +154,46 @@ select * from t1;
 d1	d2
 -1	0
 drop table t1;
+create table t1 (f float unsigned, key(f));
+insert into t1 values (NULL),(0),(0.5);
+select f, f = "-1" as eq from t1 order by f is null, f;
+f	eq
+0	0
+0.5	0
+NULL	NULL
+select f from t1 where f = "-1";
+f
+select f from t1 ignore index (f) where f = "-1";
+f
+select f from t1 where f > "-1";
+f
+0
+0.5
+select f from t1 ignore index (f) where f > "-1";
+f
+0
+0.5
+drop table t1;
+create table t1 (d double unsigned, key(d));
+insert into t1 values (NULL),(0),(0.5);
+select d, d = "-1" as eq from t1 order by d is null, d;
+d	eq
+0	0
+0.5	0
+NULL	NULL
+select d from t1 where d = "-1";
+d
+select d from t1 ignore index (d) where d = "-1";
+d
+select d from t1 where d > "-1";
+d
+0
+0.5
+select d from t1 ignore index (d) where d > "-1";
+d
+0
+0.5
+drop table t1;
 create table t1 (f float(4,3));
 insert ignore into t1 values (-11.0),(-11),("-11"),(11.0),(11),("11");
 Warnings:
diff --git a/mysql-test/main/type_float.test b/mysql-test/main/type_float.test
index adc737abe25b3..4f905d4755ddf 100644
--- a/mysql-test/main/type_float.test
+++ b/mysql-test/main/type_float.test
@@ -102,6 +102,26 @@ update ignore t1 set d2 = d1;
 select * from t1;
 drop table t1;
 
+# Do not use a truncated negative string constant for an indexed
+# FLOAT/DOUBLE UNSIGNED equality range.
+create table t1 (f float unsigned, key(f));
+insert into t1 values (NULL),(0),(0.5);
+select f, f = "-1" as eq from t1 order by f is null, f;
+select f from t1 where f = "-1";
+select f from t1 ignore index (f) where f = "-1";
+select f from t1 where f > "-1";
+select f from t1 ignore index (f) where f > "-1";
+drop table t1;
+
+create table t1 (d double unsigned, key(d));
+insert into t1 values (NULL),(0),(0.5);
+select d, d = "-1" as eq from t1 order by d is null, d;
+select d from t1 where d = "-1";
+select d from t1 ignore index (d) where d = "-1";
+select d from t1 where d > "-1";
+select d from t1 ignore index (d) where d > "-1";
+drop table t1;
+
 # Ensure that maximum values as the result of number of decimals
 # being specified in table schema are enforced (Bug #7361)
 create table t1 (f float(4,3));
diff --git a/sql/opt_range.cc b/sql/opt_range.cc
index 63fd9333c9803..86c6683e5d718 100644
--- a/sql/opt_range.cc
+++ b/sql/opt_range.cc
@@ -9665,6 +9665,18 @@ SEL_ARG *Field_num::get_mm_leaf(RANGE_OPT_PARAM *prm, KEY_PART *key_part,
   if (can_optimize_scalar_range(prm, key_part, cond, op, value) !=
       Data_type_compatibility::OK)
     DBUG_RETURN(0);
+  if (unsigned_flag &&
+      (type() == MYSQL_TYPE_FLOAT || type() == MYSQL_TYPE_DOUBLE))
+  {
+    double item_val= value->val_real();
+    if (!value->null_value && item_val < 0)
+    {
+      if (op == SCALAR_CMP_EQ || op == SCALAR_CMP_EQUAL ||
+          op == SCALAR_CMP_LT || op == SCALAR_CMP_LE)
+        DBUG_RETURN(new (prm->mem_root) SEL_ARG_IMPOSSIBLE(this));
+      DBUG_RETURN(0);
+    }
+  }
   int err= value->save_in_field_no_warnings(this, 1);
   if ((op != SCALAR_CMP_EQUAL && is_real_null()) || err < 0)
     DBUG_RETURN(&null_element);