diff --git a/dlls/msi/source.c b/dlls/msi/source.c
index e44b3a17e91..44ab0c11630 100644
--- a/dlls/msi/source.c
+++ b/dlls/msi/source.c
@@ -524,6 +524,52 @@ UINT WINAPI MsiSourceListSetInfoA(LPCSTR szProduct, LPCSTR szUserSid,
     return ret;
 }
 
+static UINT set_last_used_source(HKEY source, LPCWSTR product, LPCWSTR usersid,
+                                 MSIINSTALLCONTEXT context, DWORD options,
+                                 LPCWSTR value)
+{
+    LPWSTR buffer;
+    WCHAR typechar;
+    DWORD size;
+    UINT r;
+    int index = 0;
+
+    static const WCHAR format[] = {'%','c',';','%','i',';','%','s',0};
+
+    if (options & MSISOURCETYPE_NETWORK)
+        typechar = 'n';
+    else if (options & MSISOURCETYPE_URL)
+        typechar = 'u';
+    else
+        return ERROR_INVALID_PARAMETER;
+
+    /* make sure the source is registered */
+    r = MsiSourceListAddSourceExW(product, usersid, context,
+                                  options, value, 0);
+    if (r != ERROR_SUCCESS)
+        return r;
+
+    while ((r = MsiSourceListEnumSourcesW(product, usersid, context, options,
+                                          index, NULL, NULL)) == ERROR_SUCCESS)
+        index++;
+
+    if (r != ERROR_NO_MORE_ITEMS)
+        return r;
+
+    size = (lstrlenW(format) + lstrlenW(value) + 7) * sizeof(WCHAR);
+    buffer = msi_alloc(size);
+    if (!buffer)
+        return ERROR_OUTOFMEMORY;
+
+    sprintfW(buffer, format, typechar, index, value);
+
+    r = RegSetValueExW(source, INSTALLPROPERTY_LASTUSEDSOURCEW, 0,
+                       REG_SZ, (LPBYTE)buffer, size);
+    msi_free(buffer);
+
+    return r;
+}
+
 /******************************************************************
  *  MsiSourceListSetInfoW   (MSI.@)
  */
@@ -586,35 +632,6 @@ UINT WINAPI MsiSourceListSetInfoW( LPCWSTR szProduct, LPCWSTR szUserSid,
             RegCloseKey(media);
         }
     }
-    else if (strcmpW(szProperty, INSTALLPROPERTY_LASTUSEDSOURCEW)==0)
-    {
-        LPWSTR buffer = NULL;
-        DWORD size;
-        WCHAR typechar = 'n';
-        static const WCHAR LastUsedSource_Fmt[] = {'%','c',';','%','i',';','%','s',0};
-
-        /* make sure the source is registered */
-        MsiSourceListAddSourceExW(szProduct, szUserSid, dwContext, 
-                dwOptions, szValue, 0); 
-
-        if (dwOptions & MSISOURCETYPE_NETWORK)
-            typechar = 'n';
-        else if (dwOptions & MSISOURCETYPE_URL)
-            typechar = 'u';
-        else if (dwOptions & MSISOURCETYPE_MEDIA)
-            typechar = 'm';
-        else
-            ERR("Unknown source type! %x\n", dwOptions);
-
-        size = (lstrlenW(szValue)+5)*sizeof(WCHAR);
-        buffer = msi_alloc(size);
-        sprintfW(buffer, LastUsedSource_Fmt, typechar, 1, szValue);
-        rc = RegSetValueExW(sourcekey, INSTALLPROPERTY_LASTUSEDSOURCEW, 0, 
-                REG_EXPAND_SZ, (LPBYTE)buffer, size);
-        if (rc != ERROR_SUCCESS)
-            rc = ERROR_UNKNOWN_PROPERTY;
-        msi_free( buffer );
-    }
     else if (strcmpW(INSTALLPROPERTY_PACKAGENAMEW, szProperty)==0)
     {
         DWORD size = lstrlenW(szValue)*sizeof(WCHAR);
@@ -623,6 +640,9 @@ UINT WINAPI MsiSourceListSetInfoW( LPCWSTR szProduct, LPCWSTR szUserSid,
         if (rc != ERROR_SUCCESS)
             rc = ERROR_UNKNOWN_PROPERTY;
     }
+    else if (strcmpW(szProperty, INSTALLPROPERTY_LASTUSEDSOURCEW)==0)
+        rc = set_last_used_source(sourcekey, szProduct, szUserSid, dwContext,
+                                  dwOptions, szValue);
     else
         rc = ERROR_UNKNOWN_PROPERTY;
 
diff --git a/dlls/msi/tests/source.c b/dlls/msi/tests/source.c
index 8a275d27585..b48979547e7 100644
--- a/dlls/msi/tests/source.c
+++ b/dlls/msi/tests/source.c
@@ -1546,11 +1546,8 @@ static void test_MsiSourceListSetInfo(void)
     r = MsiSourceListSetInfoA(prodcode, NULL,
                               MSIINSTALLCONTEXT_USERUNMANAGED, MSICODE_PRODUCT,
                               INSTALLPROPERTY_LASTUSEDSOURCE, "source");
-    todo_wine
-    {
-        ok(r == ERROR_INVALID_PARAMETER,
-           "Expected ERROR_INVALID_PARAMETER, got %d\n", r);
-    }
+    ok(r == ERROR_INVALID_PARAMETER,
+       "Expected ERROR_INVALID_PARAMETER, got %d\n", r);
 
     /* INSTALLPROPERTY_LASTUSEDSOURCE, MSISOURCETYPE_NETWORK */
     r = MsiSourceListSetInfoA(prodcode, NULL,
@@ -1563,6 +1560,7 @@ static void test_MsiSourceListSetInfo(void)
     res = RegOpenKeyA(source, "Net", &net);
     ok(res == ERROR_SUCCESS, "Expected ERROR_SUCCESS, got %d\n", res);
     CHECK_REG_STR(net, "1", "source\\")
+    CHECK_REG_STR(source, "LastUsedSource", "n;1;source");
 
     /* source has forward slash */
     r = MsiSourceListSetInfoA(prodcode, NULL,
@@ -1570,7 +1568,9 @@ static void test_MsiSourceListSetInfo(void)
                               MSICODE_PRODUCT | MSISOURCETYPE_NETWORK,
                               INSTALLPROPERTY_LASTUSEDSOURCE, "source/");
     ok(r == ERROR_SUCCESS, "Expected ERROR_SUCCESS, got %d\n", r);
-    CHECK_REG_STR(net, "1", "source\\")
+    CHECK_REG_STR(net, "1", "source\\");
+    CHECK_REG_STR(net, "2", "source/\\");
+    CHECK_REG_STR(source, "LastUsedSource", "n;2;source/");
 
     /* INSTALLPROPERTY_LASTUSEDSOURCE, MSISOURCETYPE_URL */
     r = MsiSourceListSetInfoA(prodcode, NULL,
@@ -1583,6 +1583,7 @@ static void test_MsiSourceListSetInfo(void)
     res = RegOpenKeyA(source, "URL", &url);
     ok(res == ERROR_SUCCESS, "Expected ERROR_SUCCESS, got %d\n", res);
     CHECK_REG_STR(url, "1", "source/");
+    CHECK_REG_STR(source, "LastUsedSource", "u;1;source");
 
     /* source has backslash */
     r = MsiSourceListSetInfoA(prodcode, NULL,
@@ -1591,6 +1592,16 @@ static void test_MsiSourceListSetInfo(void)
                               INSTALLPROPERTY_LASTUSEDSOURCE, "source\\");
     ok(r == ERROR_SUCCESS, "Expected ERROR_SUCCESS, got %d\n", r);
     CHECK_REG_STR(url, "1", "source/");
+    CHECK_REG_STR(url, "2", "source\\/");
+    CHECK_REG_STR(source, "LastUsedSource", "u;2;source\\");
+
+    /* INSTALLPROPERTY_LASTUSEDSOURCE, MSISOURCETYPE_MEDIA */
+    r = MsiSourceListSetInfoA(prodcode, NULL,
+                              MSIINSTALLCONTEXT_USERUNMANAGED,
+                              MSICODE_PRODUCT | MSISOURCETYPE_MEDIA,
+                              INSTALLPROPERTY_LASTUSEDSOURCE, "source");
+    ok(r == ERROR_INVALID_PARAMETER,
+       "Expected ERROR_INVALID_PARAMETER, got %d\n", r);
 
     /* INSTALLPROPERTY_PACKAGENAME */
     r = MsiSourceListSetInfoA(prodcode, NULL,