diff --git a/win32ss/user/imm32/guideline.c b/win32ss/user/imm32/guideline.c
index a679e816e1e..c5bffd47dae 100644
--- a/win32ss/user/imm32/guideline.c
+++ b/win32ss/user/imm32/guideline.c
@@ -88,11 +88,16 @@ ImmGetGuideLineAW(
             }
         }
 
-        if (dwBufLen == 0 || cb == 0 || lpBuf == NULL || dwBufLen < cb)
+        if (dwBufLen == 0)
         {
             ret = cb;
             goto Quit;
         }
+        if (cb == 0 || lpBuf == NULL || dwBufLen < cb)
+        {
+            ret = 0; /* Error */
+            goto Quit;
+        }
 
         /* store to buffer */
         if (bAnsi)
@@ -149,11 +154,16 @@ ImmGetGuideLineAW(
             }
         }
 
-        if (dwBufLen == 0 || cb == 0 || lpBuf == NULL || dwBufLen < cb)
+        if (dwBufLen == 0)
         {
             ret = cb;
             goto Quit;
         }
+        if (cb == 0 || lpBuf == NULL || dwBufLen < cb)
+        {
+            ret = 0; /* Error */
+            goto Quit;
+        }
 
         /* store to buffer */
         if (bAnsi)