diff --git a/advanced_lab/c/Makefile b/advanced_lab/c/Makefile
index d2f63409be5e9357a2a206a3db5471fa0a24aed6..e0e17dbead2edc6861be47873243e3c9cea4d8c0 100644
--- a/advanced_lab/c/Makefile
+++ b/advanced_lab/c/Makefile
@@ -2,7 +2,7 @@ CC = cc
 ifeq ($(CRAY_PRGENVCRAY), loaded)
 CFLAGS = -O2 -openmp
 else ifeq ($(CRAY_PRGENVINTEL), loaded)
-CFLAGS = -O2 -openmp
+CFLAGS = -O2 -openmp -D_Float128=__float128
 else ifeq ($(CRAY_PRGENVGNU), loaded)
 CFLAGS = -O2 -fopenmp
 else