diff --git a/src/common.cu b/src/common.cu
index 04e81422f0..7706dd9a54 100644
--- a/src/common.cu
+++ b/src/common.cu
@@ -764,7 +764,12 @@ int main(int argc, char* argv[]) {
         maxBytes = (size_t)parsed;
         break;
       case 'i':
-        stepBytes = strtol(optarg, NULL, 0);
+        parsed = parsesize(optarg);
+        if (parsed < 0) {
+          fprintf(stderr, "invalid size specified for 'stepBytes'\n");
+          return -1;
+        }
+        stepBytes = (size_t)parsed;
         break;
       case 'f':
         stepFactor = strtol(optarg, NULL, 0);