diff --git a/stim/envi/bip.h b/stim/envi/bip.h
index 8314052..bce3cd5 100644
--- a/stim/envi/bip.h
+++ b/stim/envi/bip.h
@@ -1001,7 +1001,12 @@ public:
 	bool co_matrix(double* co, double* avg, unsigned char *mask, bool PROGRESS = false){
 
 #ifdef CUDA_FOUND
-		return co_matrix_cublas(co, avg, mask, PROGRESS);								//if CUDA is available, use cuBLAS to calculate the covariance matrix
+		int dev_count;
+		cudaGetDeviceCount(&dev_count);									//get the number of CUDA devices
+		cudaDeviceProp prop;
+		cudaGetDeviceProperties(&prop, 0);								//get the property of the first device
+		if(dev_count > 0 && prop.major != 9999)							//if the first device is not an emulator
+			return co_matrix_cublas(co, avg, mask, PROGRESS);			//use cuBLAS to calculate the covariance matrix
 #endif
 		progress = 0;
 		//memory allocation
--
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