diff --git a/lib/Differentiator/ReverseModeVisitor.cpp b/lib/Differentiator/ReverseModeVisitor.cpp
index 9f1eb6f6d..5909ca6e4 100644
--- a/lib/Differentiator/ReverseModeVisitor.cpp
+++ b/lib/Differentiator/ReverseModeVisitor.cpp
@@ -1459,6 +1459,10 @@ Expr* getArraySizeExpr(const ArrayType* AT, ASTContext& context,
       return StmtDiff(Clone(CE));
     }
 
+    // FIXME: Revisit this when variadic functions are supported.
+    if (FD->getNameAsString() == "printf" || FD->getNameAsString() == "fprintf")
+      return StmtDiff(Clone(CE));
+
     Expr* CUDAExecConfig = nullptr;
     if (const auto* KCE = dyn_cast<CUDAKernelCallExpr>(CE))
       CUDAExecConfig = Clone(KCE->getConfig());
diff --git a/test/CUDA/GradientKernels.cu b/test/CUDA/GradientKernels.cu
index 328a1f50d..969a1b1c1 100644
--- a/test/CUDA/GradientKernels.cu
+++ b/test/CUDA/GradientKernels.cu
@@ -436,6 +436,7 @@ double fn_memory(double *out, double *in) {
   cudaMemcpy(out_host, out, 10 * sizeof(double), cudaMemcpyDeviceToHost);
   double res = 0;
   for (int i=0; i < 10; ++i) {
+    printf("Writing result of out[%d]\n", i);
     res += out_host[i];
   }
   free(out_host);
@@ -469,6 +470,7 @@ double fn_memory(double *out, double *in) {
 //CHECK-NEXT:                break;
 //CHECK-NEXT:        }
 //CHECK-NEXT:        _t0++;
+//CHECK-NEXT:        printf("Writing result of out[%d]\n", i);
 //CHECK-NEXT:        clad::push(_t1, res);
 //CHECK-NEXT:        res += out_host[i];
 //CHECK-NEXT:    }