diff --git a/src/creatwth.cpp b/src/creatwth.cpp
index f1fdeb4f..071fc8fc 100644
--- a/src/creatwth.cpp
+++ b/src/creatwth.cpp
@@ -718,10 +718,17 @@ BOOL WINAPI DetourUpdateProcessWithDllEx(_In_ HANDLE hProcess,
         return FALSE;
     }
 #elif defined(DETOURS_64BIT)
-    if (bIs32BitProcess || bIs32BitExe) {
-        if (!UpdateImports32(hProcess, hModule, rlpDlls, nDlls)) {
+    if (bIs32BitProcess) {
+        if(bIs32BitExe) {
+            if (!UpdateImports32(hProcess, hModule, rlpDlls, nDlls)) {
+                return FALSE;
+            }
+    	}
+    	else {
+            // Can't detour a 32-bit process with 64-bit code.
+            SetLastError(ERROR_INVALID_HANDLE);
             return FALSE;
-        }
+    	}
     }
     else {
         // 64-bit native or 64-bit managed process on any platform.