diff --git a/kguebung/kguebung04/matmul/Makefile b/kguebung/kguebung04/matmul/Makefile
index 61edf2fc65cd05a0e9474c022f2161a309fdd522..a8767bf51474afce7a57e5fa5c816f0e96ecedfe 100644
--- a/kguebung/kguebung04/matmul/Makefile
+++ b/kguebung/kguebung04/matmul/Makefile
@@ -1,5 +1,5 @@
-CFLAGS = -Wall -Winvalid-pch -Wextra -Wpedantic
-LDFLAGS =
+CFLAGS = -fopenmp -Wall -Winvalid-pch -Wextra -Wpedantic
+LDFLAGS = -fopenmp
 
 binaries = matmul
 
diff --git a/kguebung/kguebung04/matmul/main.c b/kguebung/kguebung04/matmul/main.c
index 8de511dd6f387ae08b3e3b6eeb31c05e5a1d5d29..a7b4bc82569df2b031cf9985251a5e916f069f38 100644
--- a/kguebung/kguebung04/matmul/main.c
+++ b/kguebung/kguebung04/matmul/main.c
@@ -39,9 +39,11 @@ int main(int argc, char* argv[])
 
 	gettimeofday(&start, NULL);
   
+#pragma omp parallel for
 	for (i = 0; i < L; ++i) {
 		for (j = 0; j < N; ++j) {
 			double sum = 0.;
+#pragma omp simd reduction(+ : sum)
 			for (k = 0; k < M; ++k) {
 				sum += A[i][k] * B[k][j];
 			}