diff --git a/Makefile.proof b/Makefile.proof
index 931c165..8876ca0 100644
--- a/Makefile.proof
+++ b/Makefile.proof
@@ -12,7 +12,7 @@
 SPARKFLAGS += --report=fail
 SPARKFLAGS += --warnings=error
 SPARKFLAGS += --no-inlining
-SPARKFLAGS += --prover=z3 --steps=500 --timeout=1	# FIXME: timeout used because steps seems broken
+SPARKFLAGS += --prover=z3 --steps=500 --timeout=2	# FIXME: timeout used because steps seems broken
 
 quote-list = $(subst $(space),$(comma),$(patsubst %,"%",$(1)))