diff --git a/ggml.c b/ggml.c
index 200e87720e7ad4..c48c182b5640de 100644
--- a/ggml.c
+++ b/ggml.c
@@ -14574,13 +14574,14 @@ void ggml_graph_compute(struct ggml_context * ctx, struct ggml_cgraph * cgraph)
                     {
                         size_t cur = 0;
                         enum ggml_backend compute_backend = stages[GGML_TASK_COMPUTE].backend;
+                        GGML_ASSERT(compute_backend != GGML_BACKEND_UNKNOWN);
 #if defined(GGML_USE_CUBLAS)
-                        if (!= GGML_BACKEND_CPU) {
+                        if (compute_backend != GGML_BACKEND_CPU) {
                             cur = ggml_cuda_mul_mat_get_wsize(node->src0, node->src1, node);
                         }
                         else
 #elif defined(GGML_USE_CLBLAST)
-                        if (compute_backend!= GGML_BACKEND_CPU) {
+                        if (compute_backend != GGML_BACKEND_CPU) {
                             cur = ggml_cl_mul_mat_get_wsize(node->src0, node->src1, node);
                         }
                         else