diff --git a/dlls/secur32/secur32.c b/dlls/secur32/secur32.c
index f194ab77e8e..2e25b153542 100644
--- a/dlls/secur32/secur32.c
+++ b/dlls/secur32/secur32.c
@@ -163,7 +163,7 @@ PSecurityFunctionTableW WINAPI InitSecurityInterfaceW(void)
     return &securityFunctionTableW;
 }
 
-PWSTR SECUR32_strdupW(PCWSTR str)
+static PWSTR SECUR32_strdupW(PCWSTR str)
 {
     PWSTR ret;
 
diff --git a/dlls/secur32/secur32_priv.h b/dlls/secur32/secur32_priv.h
index 9eed1a57532..7b4f3ffcb8a 100644
--- a/dlls/secur32/secur32_priv.h
+++ b/dlls/secur32/secur32_priv.h
@@ -115,7 +115,6 @@ SecurePackage *SECUR32_findPackageA(PCSTR packageName);
 
 /* A few string helpers; will return NULL if str is NULL.  Free return with
  * HeapFree */
-PWSTR SECUR32_strdupW(PCWSTR str);
 PWSTR SECUR32_AllocWideFromMultiByte(PCSTR str);
 PSTR  SECUR32_AllocMultiByteFromWide(PCWSTR str);