diff --git a/src/util/env_params.cpp b/src/util/env_params.cpp
index 28d80d92d..b01a1c250 100644
--- a/src/util/env_params.cpp
+++ b/src/util/env_params.cpp
@@ -26,7 +26,7 @@ void env_params::updt_params() {
     params_ref p = gparams::get();
     set_verbosity_level(p.get_uint("verbose", get_verbosity_level()));
     enable_warning_messages(p.get_bool("warning", true));
-    memory::set_max_size(p.get_uint("memory_max_size", 0));
+    memory::set_max_size(megabytes_to_bytes(p.get_uint("memory_max_size", 0)));
     memory::set_high_watermark(p.get_uint("memory_high_watermark", 0));
 }
 
diff --git a/src/util/util.h b/src/util/util.h
index 3360c2282..8bcbce4a3 100644
--- a/src/util/util.h
+++ b/src/util/util.h
@@ -394,11 +394,14 @@ public:
 
 inline std::ostream & operator<<(std::ostream & out, escaped const & s) { s.display(out); return out; }
 
-inline unsigned long long megabytes_to_bytes(unsigned b) {
-    if (b == UINT_MAX)
-        return UINT64_MAX;
-    else
-        return static_cast<unsigned long long>(b) * 1024ull * 1024ull;
+inline size_t megabytes_to_bytes(unsigned mb) {
+    if (mb == UINT_MAX)
+        return SIZE_MAX;
+    unsigned long long b = static_cast<unsigned long long>(mb) * 1024ull * 1024ull;
+    size_t r = static_cast<size_t>(b);
+    if (r != b)  // overflow
+        r = SIZE_MAX;    
+    return r;
 }
 
 void z3_bound_num_procs();