diff --git a/Makefile b/Makefile
index 886eab13f..4eed0f33c 100644
--- a/Makefile
+++ b/Makefile
@@ -48,7 +48,7 @@ else
 endif
 
 TRIALCMD = $(shell PATH=${PATH}:${PWD}/support/bin $(PP) $(PYTHON) misc/find_trial.py)
-TRIAL=PATH=${PATH}:${PWD}/support/bin PYTHONUNBUFFERED=1 $(TRIALCMD) --rterrors $(REACTOROPT)
+TRIAL=PATH="${PATH}:${PWD}/support/bin" PYTHONUNBUFFERED=1 "$(TRIALCMD)" --rterrors "$(REACTOROPT)"
 
 .PHONY: make-version build