diff --git a/dlls/dbghelp/dbghelp.c b/dlls/dbghelp/dbghelp.c
index d7e0cf39707..54ec4efdb7c 100644
--- a/dlls/dbghelp/dbghelp.c
+++ b/dlls/dbghelp/dbghelp.c
@@ -115,6 +115,24 @@ BOOL validate_addr64(DWORD64 addr)
     return TRUE;
 }
 
+/******************************************************************
+ *		fetch_buffer
+ *
+ * Ensures process' internal buffer is large enough.
+ */
+void* fetch_buffer(struct process* pcs, unsigned size)
+{
+    if (size > pcs->buffer_size)
+    {
+        if (pcs->buffer)
+            pcs->buffer = HeapReAlloc(GetProcessHeap(), 0, pcs->buffer, size);
+        else
+            pcs->buffer = HeapAlloc(GetProcessHeap(), 0, size);
+        pcs->buffer_size = (pcs->buffer) ? size : 0;
+    }
+    return pcs->buffer;
+}
+
 /******************************************************************
  *		SymSetSearchPathW (DBGHELP.@)
  *
diff --git a/dlls/dbghelp/dbghelp.spec b/dlls/dbghelp/dbghelp.spec
index 7b3539705b6..3727474be26 100644
--- a/dlls/dbghelp/dbghelp.spec
+++ b/dlls/dbghelp/dbghelp.spec
@@ -70,7 +70,7 @@
 @ stub SymGetHomeDirectoryW
 @ stdcall SymGetLineFromAddr(long long ptr ptr)
 @ stdcall SymGetLineFromAddr64(long double ptr ptr)
-@ stub SymGetLineFromAddrW64
+@ stdcall SymGetLineFromAddrW64(long double ptr ptr)
 @ stub SymGetLineFromName
 @ stub SymGetLineFromName64
 @ stdcall SymGetLineNext(long ptr)
diff --git a/dlls/dbghelp/dbghelp_private.h b/dlls/dbghelp/dbghelp_private.h
index cfc9f92bafb..1abb2cc3ece 100644
--- a/dlls/dbghelp/dbghelp_private.h
+++ b/dlls/dbghelp/dbghelp_private.h
@@ -301,6 +301,9 @@ struct process
     unsigned long               dbg_hdr_addr;
 
     IMAGEHLP_STACK_FRAME        ctx_frame;
+
+    unsigned                    buffer_size;
+    void*                       buffer;
 };
 
 struct line_info
@@ -327,6 +330,7 @@ extern struct process* process_find_by_handle(HANDLE hProcess);
 extern HANDLE hMsvcrt;
 extern BOOL         validate_addr64(DWORD64 addr);
 extern BOOL         pcs_callback(const struct process* pcs, ULONG action, void* data);
+extern void*        fetch_buffer(struct process* pcs, unsigned size);
 
 /* elf_module.c */
 typedef BOOL (*elf_enum_modules_cb)(const char*, unsigned long addr, void* user);
diff --git a/dlls/dbghelp/symbol.c b/dlls/dbghelp/symbol.c
index 1fb1c379a6b..e2a8754ac13 100644
--- a/dlls/dbghelp/symbol.c
+++ b/dlls/dbghelp/symbol.c
@@ -1169,6 +1169,22 @@ static void copy_line_64_from_32(IMAGEHLP_LINE64* l64, const IMAGEHLP_LINE* l32)
     l64->Address = l32->Address;
 }
 
+/******************************************************************
+ *		copy_line_W64_from_32 (internal)
+ *
+ */
+static void copy_line_W64_from_32(struct process* pcs, IMAGEHLP_LINEW64* l64, const IMAGEHLP_LINE* l32)
+{
+    unsigned len;
+
+    l64->Key = l32->Key;
+    l64->LineNumber = l32->LineNumber;
+    len = MultiByteToWideChar(CP_ACP, 0, l32->FileName, -1, NULL, 0);
+    if ((l64->FileName = fetch_buffer(pcs, len * sizeof(WCHAR))))
+        MultiByteToWideChar(CP_ACP, 0, l32->FileName, -1, l64->FileName, len);
+    l64->Address = l32->Address;
+}
+
 /******************************************************************
  *		copy_line_32_from_64 (internal)
  *
@@ -1200,6 +1216,26 @@ BOOL WINAPI SymGetLineFromAddr64(HANDLE hProcess, DWORD64 dwAddr,
     return TRUE;
 }
 
+/******************************************************************
+ *		SymGetLineFromAddrW64 (DBGHELP.@)
+ *
+ */
+BOOL WINAPI SymGetLineFromAddrW64(HANDLE hProcess, DWORD64 dwAddr, 
+                                  PDWORD pdwDisplacement, PIMAGEHLP_LINEW64 Line)
+{
+    struct process*     pcs = process_find_by_handle(hProcess);
+    IMAGEHLP_LINE       line32;
+
+    if (!pcs) return FALSE;
+    if (Line->SizeOfStruct < sizeof(*Line)) return FALSE;
+    if (!validate_addr64(dwAddr)) return FALSE;
+    line32.SizeOfStruct = sizeof(line32);
+    if (!SymGetLineFromAddr(hProcess, (DWORD)dwAddr, pdwDisplacement, &line32))
+        return FALSE;
+    copy_line_W64_from_32(pcs, Line, &line32);
+    return TRUE;
+}
+
 /******************************************************************
  *		SymGetLinePrev (DBGHELP.@)
  *
diff --git a/include/dbghelp.h b/include/dbghelp.h
index 79f97b3dd7f..03442b8bfaa 100644
--- a/include/dbghelp.h
+++ b/include/dbghelp.h
@@ -217,6 +217,15 @@ typedef struct _IMAGEHLP_LINE64
     DWORD64                     Address;
 } IMAGEHLP_LINE64, *PIMAGEHLP_LINE64;
 
+typedef struct _IMAGEHLP_LINEW64
+{
+    DWORD                       SizeOfStruct;
+    PVOID                       Key;
+    DWORD                       LineNumber;
+    PWCHAR                      FileName;
+    DWORD64                     Address;
+} IMAGEHLP_LINEW64, *PIMAGEHLP_LINEW64;
+
 typedef struct _SOURCEFILE
 {
     DWORD64                     ModBase;
@@ -945,6 +954,7 @@ BOOL WINAPI SymEnumSourceFiles(HANDLE, ULONG64, PCSTR, PSYM_ENUMSOURCEFILES_CALL
                                PVOID);
 BOOL WINAPI SymGetLineFromAddr(HANDLE, DWORD, PDWORD, PIMAGEHLP_LINE);
 BOOL WINAPI SymGetLineFromAddr64(HANDLE, DWORD64, PDWORD, PIMAGEHLP_LINE64);
+BOOL WINAPI SymGetLineFromAddrW64(HANDLE, DWORD64, PDWORD, PIMAGEHLP_LINEW64);
 BOOL WINAPI SymGetLinePrev(HANDLE, PIMAGEHLP_LINE);
 BOOL WINAPI SymGetLinePrev64(HANDLE, PIMAGEHLP_LINE64);
 BOOL WINAPI SymGetLineNext(HANDLE, PIMAGEHLP_LINE);