diff --git a/capi/src/io.rs b/capi/src/io.rs
index ecf1b705..e2421f90 100644
--- a/capi/src/io.rs
+++ b/capi/src/io.rs
@@ -1709,6 +1709,24 @@ pub unsafe extern "C" fn chewing_bopomofo_String_static(
     copy_cstr(&mut ctx.bopomofo_buf, &ctx.editor.syllable_buffer_display())
 }
 
+/// # Safety
+///
+/// This function should be called with valid pointers.
+#[no_mangle]
+pub unsafe extern "C" fn chewing_bopomofo_String(ctx: *const ChewingContext) -> *mut c_char {
+    let ctx = as_ref_or_return!(
+        ctx,
+        owned_into_raw(Owned::CString, CString::default().into_raw())
+    );
+
+    let buffer = ctx.editor.syllable_buffer_display();
+    let cstr = match CString::new(buffer) {
+        Ok(cstr) => cstr,
+        Err(_) => return null_mut(),
+    };
+    owned_into_raw(Owned::CString, cstr.into_raw())
+}
+
 /// # Safety
 ///
 /// This function should be called with valid pointers.
diff --git a/capi/src/lib.rs b/capi/src/lib.rs
index c22c22ed..642a311a 100644
--- a/capi/src/lib.rs
+++ b/capi/src/lib.rs
@@ -705,6 +705,17 @@ pub mod output {
     /// </p>
     pub use super::io::chewing_zuin_Check;
 
+    /// Returns the phonetic characters in the pre-edit buffer.
+    ///
+    /// The returned value is a pointer to a character string. The memory must
+    /// be freed by the caller using function
+    /// [chewing_free][super::setup::chewing_free].
+    ///
+    /// # Failures
+    ///
+    /// This function returns NULL when memory allocation fails.
+    pub use super::io::chewing_bopomofo_String;
+
     /// Returns the phonetic characters in the pre-edit buffer.
     ///
     /// The return value is a const pointer to a character string. The pointer
diff --git a/capi/src/symbols-elf.map b/capi/src/symbols-elf.map
index 41bec920..f34df457 100644
--- a/capi/src/symbols-elf.map
+++ b/capi/src/symbols-elf.map
@@ -134,4 +134,9 @@ CHEWING_0.9 {
         chewing_version_minor;
         chewing_version_patch;
         chewing_version_extra;
-} CHEWING_0.5;
\ No newline at end of file
+} CHEWING_0.5;
+
+CHEWING_0.10 {
+    global:
+        chewing_bopomofo_String;
+} CHEWING_0.9;
\ No newline at end of file
diff --git a/capi/src/symbols-mach_o.map b/capi/src/symbols-mach_o.map
index 374e149a..fe05dfc0 100644
--- a/capi/src/symbols-mach_o.map
+++ b/capi/src/symbols-mach_o.map
@@ -3,6 +3,7 @@ _chewing_aux_Length
 _chewing_aux_String
 _chewing_aux_String_static
 _chewing_bopomofo_Check
+_chewing_bopomofo_String
 _chewing_bopomofo_String_static
 _chewing_buffer_Check
 _chewing_buffer_Len
diff --git a/capi/src/symbols-msvc.def b/capi/src/symbols-msvc.def
index 3e75d062..ea91b96c 100644
--- a/capi/src/symbols-msvc.def
+++ b/capi/src/symbols-msvc.def
@@ -4,6 +4,7 @@ EXPORTS
     chewing_aux_String;
     chewing_aux_String_static;
     chewing_bopomofo_Check;
+    chewing_bopomofo_String;
     chewing_bopomofo_String_static;
     chewing_buffer_Check;
     chewing_buffer_Len;
diff --git a/include/chewing.h b/include/chewing.h
index 8f04bb04..ca374e1f 100644
--- a/include/chewing.h
+++ b/include/chewing.h
@@ -152,7 +152,7 @@ typedef struct ChewingContext ChewingContext;
 
 #define CHEWING_VERSION_MINOR 9
 
-#define CHEWING_VERSION_PATCH 0
+#define CHEWING_VERSION_PATCH 1
 
 /**
  * Keyboard layout index.
@@ -850,6 +850,13 @@ int chewing_buffer_Len(const struct ChewingContext *ctx);
  */
 const char *chewing_bopomofo_String_static(const struct ChewingContext *ctx);
 
+/**
+ * # Safety
+ *
+ * This function should be called with valid pointers.
+ */
+char *chewing_bopomofo_String(const struct ChewingContext *ctx);
+
 /**
  * # Safety
  *
diff --git a/tests/test-error-handling.c b/tests/test-error-handling.c
index e9d5a48e..d125306d 100644
--- a/tests/test-error-handling.c
+++ b/tests/test-error-handling.c
@@ -244,6 +244,10 @@ void test_null()
     const_buf = chewing_buffer_String_static(NULL);
     ok(strcmp(const_buf, "") == 0, "chewing_buffer_String_static() returns `%s' shall be `%s'", const_buf, "");
 
+    buf = chewing_bopomofo_String(NULL);
+    ok(strcmp(buf, "") == 0, "chewing_bopomofo_String() returns `%s' shall be `%s'", buf, "");
+    chewing_free(buf);
+
     const_buf = chewing_bopomofo_String_static(NULL);
     ok(strcmp(const_buf, "") == 0, "chewing_bopomofo_String_static() returns `%s' shall be `%s'", const_buf, "");
 
diff --git a/tests/testhelper.c b/tests/testhelper.c
index 53319fd6..1cf86cc3 100644
--- a/tests/testhelper.c
+++ b/tests/testhelper.c
@@ -99,7 +99,7 @@ BufferType BOPOMOFO_BUFFER = {
     chewing_bopomofo_Check,
     chewing_zuin_Check,
     0,
-    0,
+    chewing_bopomofo_String,
     chewing_zuin_String,
     chewing_bopomofo_String_static
 };