diff --git a/dlls/pdh/pdh.spec b/dlls/pdh/pdh.spec
index 7486606db10..3d75bb190de 100644
--- a/dlls/pdh/pdh.spec
+++ b/dlls/pdh/pdh.spec
@@ -127,7 +127,7 @@
 @ stub PdhSelectDataSourceA
 @ stub PdhSelectDataSourceW
 @ stdcall PdhSetCounterScaleFactor(ptr long)
-@ stub PdhSetDefaultRealTimeDataSource
+@ stdcall PdhSetDefaultRealTimeDataSource(long)
 @ stub PdhSetLogSetRunID
 @ stub PdhSetQueryTimeRange
 @ stub PdhTranslate009CounterA
diff --git a/dlls/pdh/pdh_main.c b/dlls/pdh/pdh_main.c
index 7f08c923784..fd6deba8e77 100644
--- a/dlls/pdh/pdh_main.c
+++ b/dlls/pdh/pdh_main.c
@@ -1211,3 +1211,12 @@ PDH_STATUS WINAPI PdhEnumObjectItemsW(LPCWSTR szDataSource, LPCWSTR szMachineNam
 
     return PDH_NOT_IMPLEMENTED;
 }
+
+/***********************************************************************
+ *              PdhSetDefaultRealTimeDataSource   (PDH.@)
+ */
+PDH_STATUS WINAPI PdhSetDefaultRealTimeDataSource( DWORD source )
+{
+    FIXME("%u\n", source);
+    return ERROR_SUCCESS;
+}
diff --git a/include/pdh.h b/include/pdh.h
index d79241bf92e..f4764af3505 100644
--- a/include/pdh.h
+++ b/include/pdh.h
@@ -49,6 +49,10 @@ typedef HANDLE PDH_HLOG;
 #define PDH_FMT_1000        0x00002000
 #define PDH_FMT_NOCAP100    0x00008000
 
+#define DATA_SOURCE_REGISTRY    0x00000001
+#define DATA_SOURCE_LOGFILE     0x00000002
+#define DATA_SOURCE_WBEM        0x00000004
+
 typedef struct _PDH_FMT_COUNTERVALUE
 {
     DWORD CStatus;
@@ -198,6 +202,7 @@ PDH_STATUS WINAPI PdhOpenQueryW(LPCWSTR, DWORD_PTR, PDH_HQUERY *);
 #define    PdhOpenQuery WINELIB_NAME_AW(PdhOpenQuery)
 PDH_STATUS WINAPI PdhRemoveCounter(PDH_HCOUNTER);
 PDH_STATUS WINAPI PdhSetCounterScaleFactor(PDH_HCOUNTER, LONG);
+PDH_STATUS WINAPI PdhSetDefaultRealTimeDataSource(DWORD);
 PDH_STATUS WINAPI PdhValidatePathA(LPCSTR);
 PDH_STATUS WINAPI PdhValidatePathW(LPCWSTR);
 #define    PdhValidatePath WINELIB_NAME_AW(PdhValidatePath)