diff --git a/trunk/src/kernel/srs_kernel_utility.cpp b/trunk/src/kernel/srs_kernel_utility.cpp
index 60eef5ddb6..aebee90c59 100644
--- a/trunk/src/kernel/srs_kernel_utility.cpp
+++ b/trunk/src/kernel/srs_kernel_utility.cpp
@@ -222,7 +222,7 @@ string srs_string_trim_end(string str, string trim_chars)
             ret.erase(ret.end() - 1);
             
             // ok, matched, should reset the search
-            i = 0;
+            i = -1;
         }
     }
     
@@ -240,7 +240,7 @@ string srs_string_trim_start(string str, string trim_chars)
             ret.erase(ret.begin());
             
             // ok, matched, should reset the search
-            i = 0;
+            i = -1;
         }
     }
     
@@ -259,7 +259,7 @@ string srs_string_remove(string str, string remove_chars)
                 it = ret.erase(it);
                 
                 // ok, matched, should reset the search
-                i = 0;
+                i = -1;
             } else {
                 ++it;
             }
diff --git a/trunk/src/utest/srs_utest_kernel.cpp b/trunk/src/utest/srs_utest_kernel.cpp
index 93c69c80c8..46e82bcda3 100644
--- a/trunk/src/utest/srs_utest_kernel.cpp
+++ b/trunk/src/utest/srs_utest_kernel.cpp
@@ -1487,6 +1487,15 @@ VOID TEST(KernelUtilityTest, UtilityString)
     
     str1 = srs_string_replace(str, "o", "XX");
     EXPECT_STREQ("HellXX, WXXrld! HellXX, SRS!", str1.c_str());
+
+    str1 = srs_string_trim_start(str, "x");
+    EXPECT_STREQ("Hello, World! Hello, SRS!", str1.c_str());
+
+    str1 = srs_string_trim_start(str, "S!R");
+    EXPECT_STREQ("Hello, World! Hello, SRS!", str1.c_str());
+
+    str1 = srs_string_trim_start(str, "lHe");
+    EXPECT_STREQ("o, World! Hello, SRS!", str1.c_str());
     
     str1 = srs_string_trim_end(str, "x");
     EXPECT_STREQ("Hello, World! Hello, SRS!", str1.c_str());
@@ -1494,7 +1503,7 @@ VOID TEST(KernelUtilityTest, UtilityString)
     str1 = srs_string_trim_end(str, "He");
     EXPECT_STREQ("Hello, World! Hello, SRS!", str1.c_str());
     
-    str1 = srs_string_trim_end(str, "HeS!R");
+    str1 = srs_string_trim_end(str, "S!R");
     EXPECT_STREQ("Hello, World! Hello, ", str1.c_str());
     
     str1 = srs_string_remove(str, "x");