diff --git a/src/nfa/castlecompile.cpp b/src/nfa/castlecompile.cpp
index 3505e08a..b709d3c5 100644
--- a/src/nfa/castlecompile.cpp
+++ b/src/nfa/castlecompile.cpp
@@ -883,7 +883,7 @@ bool is_equal(const CastleProto &c1, const CastleProto &c2) {
 }
 
 bool requiresDedupe(const CastleProto &proto,
-                    const ue2::flat_set<ReportID> &reports) {
+                    const flat_set<ReportID> &reports) {
     for (const auto &report : reports) {
         auto it = proto.report_map.find(report);
         if (it == end(proto.report_map)) {
diff --git a/src/nfa/goughcompile_internal.h b/src/nfa/goughcompile_internal.h
index 9de88c77..e6454052 100644
--- a/src/nfa/goughcompile_internal.h
+++ b/src/nfa/goughcompile_internal.h
@@ -106,10 +106,10 @@ struct GoughSSAVarJoin;
 struct GoughSSAVar : noncopyable {
     GoughSSAVar(void) : seen(false), slot(INVALID_SLOT) {}
     virtual ~GoughSSAVar();
-    const ue2::flat_set<GoughSSAVar *> &get_inputs() const {
+    const flat_set<GoughSSAVar *> &get_inputs() const {
         return inputs;
     }
-    const ue2::flat_set<GoughSSAVarWithInputs *> &get_outputs() const {
+    const flat_set<GoughSSAVarWithInputs *> &get_outputs() const {
         return outputs;
     }
     virtual void replace_input(GoughSSAVar *old_v, GoughSSAVar *new_v) = 0;
@@ -127,8 +127,8 @@ struct GoughSSAVar : noncopyable {
         clear_outputs();
     }
 protected:
-    ue2::flat_set<GoughSSAVar *> inputs;
-    ue2::flat_set<GoughSSAVarWithInputs *> outputs;
+    flat_set<GoughSSAVar *> inputs;
+    flat_set<GoughSSAVarWithInputs *> outputs;
     friend struct GoughSSAVarWithInputs;
     friend struct GoughSSAVarMin;
     friend struct GoughSSAVarJoin;
@@ -184,16 +184,14 @@ struct GoughSSAVarJoin : public GoughSSAVarWithInputs {
 
     void add_input(GoughSSAVar *v, GoughEdge prev);
 
-    const ue2::flat_set<GoughEdge> &get_edges_for_input(GoughSSAVar *input)
-        const;
-    const std::map<GoughSSAVar *, ue2::flat_set<GoughEdge> > &get_input_map()
-        const;
+    const flat_set<GoughEdge> &get_edges_for_input(GoughSSAVar *input) const;
+    const std::map<GoughSSAVar *, flat_set<GoughEdge>> &get_input_map() const;
 
 protected:
     void remove_input_raw(GoughSSAVar *v) override;
 
 private:
-    std::map<GoughSSAVar *, ue2::flat_set<GoughEdge>> input_map;
+    std::map<GoughSSAVar *, flat_set<GoughEdge>> input_map;
 };
 
 struct gough_accel_state_info {
diff --git a/src/nfagraph/ng_fixed_width.cpp b/src/nfagraph/ng_fixed_width.cpp
index 978dad44..8fb264d8 100644
--- a/src/nfagraph/ng_fixed_width.cpp
+++ b/src/nfagraph/ng_fixed_width.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015-2016, Intel Corporation
+ * Copyright (c) 2015-2017, Intel Corporation
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
@@ -48,7 +48,7 @@ namespace ue2 {
 
 static
 bool findMask(const NGHolder &g, vector<CharReach> *mask, bool *anchored,
-              ue2::flat_set<ReportID> *reports) {
+              flat_set<ReportID> *reports) {
     DEBUG_PRINTF("looking for a mask pattern\n");
     set<NFAVertex> s_succ;
     insert(&s_succ, adjacent_vertices(g.start, g));
@@ -117,7 +117,7 @@ bool handleFixedWidth(RoseBuild &rose, const NGHolder &g, const Grey &grey) {
         return false;
     }
 
-    ue2::flat_set<ReportID> reports;
+    flat_set<ReportID> reports;
     bool anchored = false;
     vector<CharReach> mask;
 
diff --git a/src/nfagraph/ng_holder.h b/src/nfagraph/ng_holder.h
index f61c476a..36cf6244 100644
--- a/src/nfagraph/ng_holder.h
+++ b/src/nfagraph/ng_holder.h
@@ -67,7 +67,7 @@ struct NFAGraphEdgeProps {
 
     /** \brief For graphs that will be implemented as multi-top engines, this
      * specifies the top events. Only used on edges from the start vertex. */
-    ue2::flat_set<u32> tops;
+    flat_set<u32> tops;
 
     /** \brief Flags associated with assertions. */
     u32 assert_flags = 0;
diff --git a/src/nfagraph/ng_limex_accel.cpp b/src/nfagraph/ng_limex_accel.cpp
index 80e08a7f..fa46a42c 100644
--- a/src/nfagraph/ng_limex_accel.cpp
+++ b/src/nfagraph/ng_limex_accel.cpp
@@ -335,7 +335,7 @@ struct DAccelScheme {
         return false;
     }
 
-    ue2::flat_set<std::pair<u8, u8> > double_byte;
+    flat_set<pair<u8, u8>> double_byte;
     CharReach double_cr;
     u32 double_offset = 0;
 };
diff --git a/src/nfagraph/ng_limex_accel.h b/src/nfagraph/ng_limex_accel.h
index 4c3d2b91..f6f7f1b3 100644
--- a/src/nfagraph/ng_limex_accel.h
+++ b/src/nfagraph/ng_limex_accel.h
@@ -57,8 +57,7 @@ struct CompileContext;
 
 void findAccelFriends(const NGHolder &g, NFAVertex v,
                   const std::map<NFAVertex, BoundedRepeatSummary> &br_cyclic,
-                      u32 offset,
-                      ue2::flat_set<NFAVertex> *friends);
+                  u32 offset, flat_set<NFAVertex> *friends);
 
 #define DOUBLE_SHUFTI_LIMIT 20
 
diff --git a/src/nfagraph/ng_literal_decorated.cpp b/src/nfagraph/ng_literal_decorated.cpp
index 1a8cafac..61a31dbf 100644
--- a/src/nfagraph/ng_literal_decorated.cpp
+++ b/src/nfagraph/ng_literal_decorated.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015-2016, Intel Corporation
+ * Copyright (c) 2015-2017, Intel Corporation
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
@@ -192,7 +192,7 @@ struct PathMask {
     }
 
     vector<CharReach> mask;
-    ue2::flat_set<ReportID> reports;
+    flat_set<ReportID> reports;
     bool is_anchored;
     bool is_eod;
 };
diff --git a/src/nfagraph/ng_repeat.cpp b/src/nfagraph/ng_repeat.cpp
index da42b36d..7add6557 100644
--- a/src/nfagraph/ng_repeat.cpp
+++ b/src/nfagraph/ng_repeat.cpp
@@ -1598,7 +1598,7 @@ vector<CharReach> getUnionedTrigger(const NGHolder &g, const NFAVertex v) {
 
     vector<CharReach> trigger;
 
-    ue2::flat_set<NFAVertex> curr, next;
+    flat_set<NFAVertex> curr, next;
     insert(&curr, inv_adjacent_vertices(v, g));
 
     if (contains(curr, g.start)) {
@@ -2234,7 +2234,7 @@ void analyseRepeats(NGHolder &g, const ReportManager *rm,
 #ifndef NDEBUG
     // So we can assert that the number of tops hasn't changed at the end of
     // this analysis.
-    const ue2::flat_set<u32> allTops = getTops(g);
+    const flat_set<u32> allTops = getTops(g);
 #endif
 
     // Later on, we're (a little bit) dependent on depth information for
diff --git a/src/nfagraph/ng_small_literal_set.cpp b/src/nfagraph/ng_small_literal_set.cpp
index fb191efa..9c2d9ba3 100644
--- a/src/nfagraph/ng_small_literal_set.cpp
+++ b/src/nfagraph/ng_small_literal_set.cpp
@@ -100,7 +100,7 @@ bool operator<(const sls_literal &a, const sls_literal &b) {
 
 static
 bool checkLongMixedSensitivityLiterals(
-        const map<sls_literal, ue2::flat_set<ReportID>> &literals) {
+        const map<sls_literal, flat_set<ReportID>> &literals) {
     const size_t len = MAX_MASK2_WIDTH;
 
     for (const sls_literal &lit : literals | map_keys) {
@@ -114,7 +114,7 @@ bool checkLongMixedSensitivityLiterals(
 
 static
 bool findLiterals(const NGHolder &g,
-                  map<sls_literal, ue2::flat_set<ReportID>> *literals) {
+                  map<sls_literal, flat_set<ReportID>> *literals) {
     vector<NFAVertex> order = getTopoOrdering(g);
 
     vector<set<sls_literal>> built(num_vertices(g));
@@ -198,7 +198,7 @@ bool findLiterals(const NGHolder &g,
 }
 
 static
-size_t min_period(const map<sls_literal, ue2::flat_set<ReportID>> &literals) {
+size_t min_period(const map<sls_literal, flat_set<ReportID>> &literals) {
     size_t rv = SIZE_MAX;
 
     for (const sls_literal &lit : literals | map_keys) {
@@ -229,7 +229,7 @@ bool handleSmallLiteralSets(RoseBuild &rose, const NGHolder &g,
 
     DEBUG_PRINTF("looking for literals\n");
 
-    map<sls_literal, ue2::flat_set<ReportID>> literals;
+    map<sls_literal, flat_set<ReportID>> literals;
     if (!findLiterals(g, &literals)) {
         DEBUG_PRINTF(":(\n");
         return false;
diff --git a/src/nfagraph/ng_som.cpp b/src/nfagraph/ng_som.cpp
index 6520a590..45917b45 100644
--- a/src/nfagraph/ng_som.cpp
+++ b/src/nfagraph/ng_som.cpp
@@ -267,7 +267,7 @@ bool validateEXSL(const NGHolder &g,
     const vector<CharReach> escapes_vec(1, escapes);
     const vector<CharReach> notescapes_vec(1, ~escapes);
 
-    ue2::flat_set<NFAVertex> states;
+    flat_set<NFAVertex> states;
     /* turn on all states past the prefix */
     DEBUG_PRINTF("region %u is cutover\n", region);
     for (auto v : vertices_range(g)) {
@@ -280,7 +280,7 @@ bool validateEXSL(const NGHolder &g,
     states = execute_graph(g, escapes_vec, states);
 
     /* flood with any number of not escapes */
-    ue2::flat_set<NFAVertex> prev_states;
+    flat_set<NFAVertex> prev_states;
     while (prev_states != states) {
         prev_states = states;
         states = execute_graph(g, notescapes_vec, states);
@@ -290,7 +290,7 @@ bool validateEXSL(const NGHolder &g,
     /* find input starts to use for when we are running the prefix through as
      * when the escape character arrives we may be in matching the prefix
      * already */
-    ue2::flat_set<NFAVertex> prefix_start_states;
+    flat_set<NFAVertex> prefix_start_states;
     for (auto v : vertices_range(prefix)) {
         if (v != prefix.accept && v != prefix.acceptEod
             /* and as we have already made it past the prefix once */
diff --git a/src/nfagraph/ng_util.cpp b/src/nfagraph/ng_util.cpp
index 83b29257..59c73498 100644
--- a/src/nfagraph/ng_util.cpp
+++ b/src/nfagraph/ng_util.cpp
@@ -450,8 +450,8 @@ void appendLiteral(NGHolder &h, const ue2_literal &s) {
     }
 }
 
-ue2::flat_set<u32> getTops(const NGHolder &h) {
-    ue2::flat_set<u32> tops;
+flat_set<u32> getTops(const NGHolder &h) {
+    flat_set<u32> tops;
     for (const auto &e : out_edges_range(h.start, h)) {
         insert(&tops, h[e].tops);
     }
diff --git a/src/parser/Parser.rl b/src/parser/Parser.rl
index 43dfc760..8643aebf 100644
--- a/src/parser/Parser.rl
+++ b/src/parser/Parser.rl
@@ -1950,7 +1950,7 @@ unique_ptr<Component> parse(const char *ptr, ParseMode &globalMode) {
     unsigned groupIndex = 1;
 
     // Set storing group names that are currently in use.
-    ue2::flat_set<string> groupNames;
+    flat_set<string> groupNames;
 
     // Root sequence.
     unique_ptr<ComponentSequence> rootSeq = ue2::make_unique<ComponentSequence>();
diff --git a/src/parser/check_refs.cpp b/src/parser/check_refs.cpp
index 0badc780..60b5b6ba 100644
--- a/src/parser/check_refs.cpp
+++ b/src/parser/check_refs.cpp
@@ -114,7 +114,7 @@ public:
 ReferenceVisitor::~ReferenceVisitor() {}
 
 void checkReferences(const Component &root, unsigned int groupIndices,
-                     const ue2::flat_set<std::string> &groupNames) {
+                     const flat_set<std::string> &groupNames) {
     ReferenceVisitor vis(groupIndices, groupNames);
     root.accept(vis);
 }
diff --git a/src/rose/rose_build_add.cpp b/src/rose/rose_build_add.cpp
index f36fa576..b003336a 100644
--- a/src/rose/rose_build_add.cpp
+++ b/src/rose/rose_build_add.cpp
@@ -121,7 +121,7 @@ RoseVertex createVertex(RoseBuildImpl *build, u32 literalId, u32 min_offset,
 RoseVertex createVertex(RoseBuildImpl *build, const RoseVertex parent,
                         u32 minBound, u32 maxBound, u32 literalId,
                         size_t literalLength,
-                        const ue2::flat_set<ReportID> &reports) {
+                        const flat_set<ReportID> &reports) {
     assert(parent != RoseGraph::null_vertex());
 
     RoseGraph &g = build->g;
@@ -1641,7 +1641,7 @@ bool roseCheckRose(const RoseInGraph &ig, bool prefilter,
 }
 
 void RoseBuildImpl::add(bool anchored, bool eod, const ue2_literal &lit,
-                        const ue2::flat_set<ReportID> &reports) {
+                        const flat_set<ReportID> &reports) {
     assert(!reports.empty());
 
     if (cc.grey.floodAsPuffette && !anchored && !eod && is_flood(lit) &&
diff --git a/src/rose/rose_build_add_internal.h b/src/rose/rose_build_add_internal.h
index 569485a4..143f1dfa 100644
--- a/src/rose/rose_build_add_internal.h
+++ b/src/rose/rose_build_add_internal.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015, Intel Corporation
+ * Copyright (c) 2015-2017, Intel Corporation
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
@@ -31,8 +31,7 @@
 
 #include "rose_graph.h"
 #include "ue2common.h"
-
-#include <set>
+#include "util/flat_containers.h"
 
 namespace ue2 {
 
@@ -41,8 +40,8 @@ class RoseBuildImpl;
 RoseVertex createVertex(RoseBuildImpl *build, const RoseVertex parent,
                         u32 minBound, u32 maxBound, u32 literalId,
                         size_t literalLength,
-                        const ue2::flat_set<ReportID> &reports);
+                        const flat_set<ReportID> &reports);
 
 } // namespace ue2
 
-#endif
+#endif // ROSE_BUILD_ADD_INTERNAL_H
diff --git a/src/rose/rose_build_add_mask.cpp b/src/rose/rose_build_add_mask.cpp
index bd8eed0c..c60c053e 100644
--- a/src/rose/rose_build_add_mask.cpp
+++ b/src/rose/rose_build_add_mask.cpp
@@ -414,8 +414,8 @@ bool validateTransientMask(const vector<CharReach> &mask, bool anchored,
 
 static
 bool maskIsNeeded(const ue2_literal &lit, const NGHolder &g) {
-    ue2::flat_set<NFAVertex> curr = {g.accept};
-    ue2::flat_set<NFAVertex> next;
+    flat_set<NFAVertex> curr = {g.accept};
+    flat_set<NFAVertex> next;
 
     for (auto it = lit.rbegin(), ite = lit.rend(); it != ite; ++it) {
         const CharReach &cr = *it;
@@ -451,7 +451,7 @@ bool maskIsNeeded(const ue2_literal &lit, const NGHolder &g) {
 
 static
 void addTransientMask(RoseBuildImpl &build, const vector<CharReach> &mask,
-                      const ue2::flat_set<ReportID> &reports, bool anchored,
+                      const flat_set<ReportID> &reports, bool anchored,
                       bool eod) {
     vector<ue2_literal> lits;
     u32 lit_minBound; /* minBound of each literal in lit */
@@ -516,7 +516,7 @@ void addTransientMask(RoseBuildImpl &build, const vector<CharReach> &mask,
         ENSURE_AT_LEAST(&build.ematcher_region_size, mask.size());
     }
 
-    const ue2::flat_set<ReportID> no_reports;
+    const flat_set<ReportID> no_reports;
 
     for (const auto &lit : lits) {
         u32 lit_id = build.getLiteralId(lit, msk, cmp, delay, table);
@@ -553,7 +553,7 @@ void addTransientMask(RoseBuildImpl &build, const vector<CharReach> &mask,
 }
 
 static
-unique_ptr<NGHolder> buildMaskRhs(const ue2::flat_set<ReportID> &reports,
+unique_ptr<NGHolder> buildMaskRhs(const flat_set<ReportID> &reports,
                                   const vector<CharReach> &mask,
                                   u32 suffix_len) {
     assert(suffix_len);
@@ -581,10 +581,9 @@ unique_ptr<NGHolder> buildMaskRhs(const ue2::flat_set<ReportID> &reports,
 }
 
 static
-void doAddMask(RoseBuildImpl &tbi, bool anchored,
-               const vector<CharReach> &mask, const ue2_literal &lit,
-               u32 prefix_len, u32 suffix_len,
-               const ue2::flat_set<ReportID> &reports) {
+void doAddMask(RoseBuildImpl &tbi, bool anchored, const vector<CharReach> &mask,
+               const ue2_literal &lit, u32 prefix_len, u32 suffix_len,
+               const flat_set<ReportID> &reports) {
     /* Note: bounds are relative to literal start */
     RoseInGraph ig;
     RoseInVertex s = add_vertex(RoseInVertexProps::makeStart(anchored), ig);
@@ -711,7 +710,7 @@ bool checkAllowMask(const vector<CharReach> &mask, ue2_literal *lit,
 }
 
 bool RoseBuildImpl::add(bool anchored, const vector<CharReach> &mask,
-                        const ue2::flat_set<ReportID> &reports) {
+                        const flat_set<ReportID> &reports) {
     if (validateTransientMask(mask, anchored, false, cc.grey)) {
         bool eod = false;
         addTransientMask(*this, mask, reports, anchored, eod);
@@ -734,14 +733,14 @@ bool RoseBuildImpl::add(bool anchored, const vector<CharReach> &mask,
 }
 
 bool RoseBuildImpl::validateMask(const vector<CharReach> &mask,
-                                 UNUSED const ue2::flat_set<ReportID> &reports,
+                                 UNUSED const flat_set<ReportID> &reports,
                                  bool anchored, bool eod) const {
     return validateTransientMask(mask, anchored, eod, cc.grey);
 }
 
 static
 unique_ptr<NGHolder> makeAnchoredGraph(const vector<CharReach> &mask,
-                                       const ue2::flat_set<ReportID> &reports,
+                                       const flat_set<ReportID> &reports,
                                        bool eod) {
     auto gp = ue2::make_unique<NGHolder>();
     NGHolder &g = *gp;
@@ -763,7 +762,7 @@ unique_ptr<NGHolder> makeAnchoredGraph(const vector<CharReach> &mask,
 
 static
 bool addAnchoredMask(RoseBuildImpl &build, const vector<CharReach> &mask,
-                     const ue2::flat_set<ReportID> &reports, bool eod) {
+                     const flat_set<ReportID> &reports, bool eod) {
     if (!build.cc.grey.allowAnchoredAcyclic) {
         return false;
     }
@@ -775,8 +774,8 @@ bool addAnchoredMask(RoseBuildImpl &build, const vector<CharReach> &mask,
 }
 
 void RoseBuildImpl::addMask(const vector<CharReach> &mask,
-                            const ue2::flat_set<ReportID> &reports,
-                            bool anchored, bool eod) {
+                            const flat_set<ReportID> &reports, bool anchored,
+                            bool eod) {
     if (anchored && addAnchoredMask(*this, mask, reports, eod)) {
         DEBUG_PRINTF("added mask as anchored acyclic graph\n");
         return;
diff --git a/src/rose/rose_build_compile.cpp b/src/rose/rose_build_compile.cpp
index e24d0b2e..1cf3bbe6 100644
--- a/src/rose/rose_build_compile.cpp
+++ b/src/rose/rose_build_compile.cpp
@@ -1087,13 +1087,13 @@ bool triggerKillsRoseGraph(const RoseBuildImpl &build, const left_id &left,
     assert(left.graph());
     const NGHolder &h = *left.graph();
 
-    ue2::flat_set<NFAVertex> all_states;
+    flat_set<NFAVertex> all_states;
     insert(&all_states, vertices(h));
     assert(out_degree(h.startDs, h) == 1); /* triggered don't use sds */
     DEBUG_PRINTF("removing sds\n");
     all_states.erase(h.startDs);
 
-    ue2::flat_set<NFAVertex> states;
+    flat_set<NFAVertex> states;
 
     /* check each pred literal to see if they all kill previous graph
      * state */
diff --git a/src/rose/rose_build_dedupe.cpp b/src/rose/rose_build_dedupe.cpp
index d3e72313..04144f56 100644
--- a/src/rose/rose_build_dedupe.cpp
+++ b/src/rose/rose_build_dedupe.cpp
@@ -39,7 +39,7 @@ using namespace std;
 namespace ue2 {
 
 static
-bool requiresDedupe(const NGHolder &h, const ue2::flat_set<ReportID> &reports,
+bool requiresDedupe(const NGHolder &h, const flat_set<ReportID> &reports,
                     const Grey &grey) {
     /* TODO: tighten */
     NFAVertex seen_vert = NGHolder::null_vertex();
@@ -83,10 +83,10 @@ class RoseDedupeAuxImpl : public RoseDedupeAux {
 public:
     explicit RoseDedupeAuxImpl(const RoseBuildImpl &build_in);
     bool requiresDedupeSupport(
-        const ue2::flat_set<ReportID> &reports) const override;
+        const flat_set<ReportID> &reports) const override;
 
 private:
-    bool hasSafeMultiReports(const ue2::flat_set<ReportID> &reports) const;
+    bool hasSafeMultiReports(const flat_set<ReportID> &reports) const;
 
     const RoseBuildImpl &build;
     map<ReportID, set<RoseVertex>> vert_map; //!< ordinary literals
diff --git a/src/rose/rose_build_exclusive.cpp b/src/rose/rose_build_exclusive.cpp
index 25585ec0..4c8796f5 100644
--- a/src/rose/rose_build_exclusive.cpp
+++ b/src/rose/rose_build_exclusive.cpp
@@ -26,9 +26,9 @@
  * POSSIBILITY OF SUCH DAMAGE.
  */
 
-#include "ue2common.h"
-
 #include "rose_build_exclusive.h"
+
+#include "ue2common.h"
 #include "rose_build_merge.h"
 #include "nfa/castlecompile.h"
 #include "nfagraph/ng_execute.h"
@@ -37,6 +37,7 @@
 #include "util/clique.h"
 #include "util/compile_context.h"
 #include "util/container.h"
+#include "util/flat_containers.h"
 #include "util/graph.h"
 #include "util/make_unique.h"
 
@@ -228,7 +229,7 @@ bool isExclusive(const NGHolder &h,
                 lower_bound = ~0U;
             }
 
-            ue2::flat_set<NFAVertex> states;
+            flat_set<NFAVertex> states;
             for (const auto &v : vertices_range(h)) {
                 if (h[v].index >= lower_bound || h[v].index < 2) {
                     states.insert(v);
diff --git a/src/rose/rose_build_merge.cpp b/src/rose/rose_build_merge.cpp
index 15a1ae78..5d4d46e4 100644
--- a/src/rose/rose_build_merge.cpp
+++ b/src/rose/rose_build_merge.cpp
@@ -1738,7 +1738,7 @@ void dedupeLeftfixesVariableLag(RoseBuildImpl &tbi) {
 }
 
 static
-u32 findUnusedTop(const ue2::flat_set<u32> &tops) {
+u32 findUnusedTop(const flat_set<u32> &tops) {
     u32 i = 0;
     while (contains(tops, i)) {
         i++;
@@ -1766,7 +1766,7 @@ void replaceTops(NGHolder &h, const map<u32, u32> &top_mapping) {
 static
 bool setDistinctTops(NGHolder &h1, const NGHolder &h2,
                      map<u32, u32> &top_mapping) {
-    ue2::flat_set<u32> tops1 = getTops(h1), tops2 = getTops(h2);
+    flat_set<u32> tops1 = getTops(h1), tops2 = getTops(h2);
 
     DEBUG_PRINTF("before: h1 has %zu tops, h2 has %zu tops\n", tops1.size(),
                  tops2.size());
diff --git a/src/util/graph.h b/src/util/graph.h
index 9d6bb955..660afd02 100644
--- a/src/util/graph.h
+++ b/src/util/graph.h
@@ -146,7 +146,7 @@ void find_unreachable(const Graph &g, const SourceCont &sources, OutCont *out) {
 }
 
 template <class Graph>
-ue2::flat_set<typename Graph::vertex_descriptor>
+flat_set<typename Graph::vertex_descriptor>
 find_vertices_in_cycles(const Graph &g) {
     using vertex_descriptor = typename Graph::vertex_descriptor;
 
@@ -160,7 +160,7 @@ find_vertices_in_cycles(const Graph &g) {
         comps[e.second].push_back(e.first);
     }
 
-    ue2::flat_set<vertex_descriptor> rv;
+    flat_set<vertex_descriptor> rv;
 
     for (const auto &comp : comps | boost::adaptors::map_values) {
         /* every vertex in a strongly connected component is reachable from
diff --git a/src/util/partitioned_set.h b/src/util/partitioned_set.h
index 41710fe7..313c08e1 100644
--- a/src/util/partitioned_set.h
+++ b/src/util/partitioned_set.h
@@ -98,8 +98,7 @@ public:
      * If the set was not split (due to there being no overlap with splitter or
      * being a complete subset), INVALID_SUBSET is returned.
      */
-    size_t split(size_t subset_index,
-                 const typename ue2::flat_set<T> &splitter) {
+    size_t split(size_t subset_index, const flat_set<T> &splitter) {
         assert(!splitter.empty());
         if (splitter.empty()) {
             return INVALID_SUBSET;
@@ -193,7 +192,7 @@ public:
     /**
      * Returns all subsets which have a member in keys.
      */
-    void find_overlapping(const typename ue2::flat_set<T> &keys,
+    void find_overlapping(const flat_set<T> &keys,
                           std::vector<size_t> *containing) const {
         boost::dynamic_bitset<> seen(subsets.size()); // all zero by default.
 
diff --git a/src/util/report_manager.cpp b/src/util/report_manager.cpp
index a846eb25..c0e9ee15 100644
--- a/src/util/report_manager.cpp
+++ b/src/util/report_manager.cpp
@@ -133,7 +133,7 @@ vector<ReportID> ReportManager::getDkeyToReportTable() const {
 void ReportManager::assignDkeys(const RoseBuild *rose) {
     DEBUG_PRINTF("assigning...\n");
 
-    map<u32, ue2::flat_set<ReportID>> ext_to_int;
+    map<u32, flat_set<ReportID>> ext_to_int;
 
     for (u32 i = 0; i < reportIds.size(); i++) {
         const Report &ir = reportIds[i];