diff --git a/dtool/src/dtoolutil/dSearchPath.h b/dtool/src/dtoolutil/dSearchPath.h
index 7258a71f26..8a13ebf063 100644
--- a/dtool/src/dtoolutil/dSearchPath.h
+++ b/dtool/src/dtoolutil/dSearchPath.h
@@ -53,8 +53,8 @@ PUBLISHED:
   };
 
   DSearchPath() = default;
-  DSearchPath(const std::string &path, const std::string &separator = std::string());
-  DSearchPath(const Filename &directory);
+  explicit DSearchPath(const std::string &path, const std::string &separator = std::string());
+  explicit DSearchPath(const Filename &directory);
   DSearchPath(const DSearchPath &copy) = default;
   DSearchPath(DSearchPath &&from) = default;
   ~DSearchPath() = default;
diff --git a/dtool/src/dtoolutil/filename.h b/dtool/src/dtoolutil/filename.h
index db0728f95c..f3065034ca 100644
--- a/dtool/src/dtoolutil/filename.h
+++ b/dtool/src/dtoolutil/filename.h
@@ -63,7 +63,7 @@ public:
 
 PUBLISHED:
   INLINE Filename();
-  Filename(const Filename &dirname, const Filename &basename);
+  explicit Filename(const Filename &dirname, const Filename &basename);
 
 #ifdef HAVE_PYTHON
   EXTENSION(Filename(PyObject *path));
diff --git a/dtool/src/prc/configVariableBool.h b/dtool/src/prc/configVariableBool.h
index c2c4da14c7..94ba8853bd 100644
--- a/dtool/src/prc/configVariableBool.h
+++ b/dtool/src/prc/configVariableBool.h
@@ -22,7 +22,7 @@
  */
 class EXPCL_DTOOL_PRC ConfigVariableBool : public ConfigVariable {
 PUBLISHED:
-  INLINE ConfigVariableBool(const std::string &name);
+  INLINE explicit ConfigVariableBool(const std::string &name);
   INLINE ConfigVariableBool(const std::string &name, bool default_value,
                             const std::string &description = std::string(), int flags = 0);
   INLINE ConfigVariableBool(const std::string &name, const std::string &default_value,
diff --git a/dtool/src/prc/configVariableDouble.h b/dtool/src/prc/configVariableDouble.h
index 816c4cbf35..6244ae8f15 100644
--- a/dtool/src/prc/configVariableDouble.h
+++ b/dtool/src/prc/configVariableDouble.h
@@ -23,7 +23,7 @@
  */
 class EXPCL_DTOOL_PRC ConfigVariableDouble : public ConfigVariable {
 PUBLISHED:
-  INLINE ConfigVariableDouble(const std::string &name);
+  INLINE explicit ConfigVariableDouble(const std::string &name);
   INLINE ConfigVariableDouble(const std::string &name, double default_value,
                               const std::string &description = std::string(),
                               int flags = 0);
diff --git a/dtool/src/prc/configVariableFilename.h b/dtool/src/prc/configVariableFilename.h
index c6677a7ec9..5d01702917 100644
--- a/dtool/src/prc/configVariableFilename.h
+++ b/dtool/src/prc/configVariableFilename.h
@@ -26,7 +26,7 @@
  */
 class EXPCL_DTOOL_PRC ConfigVariableFilename : public ConfigVariable {
 PUBLISHED:
-  INLINE ConfigVariableFilename(const std::string &name);
+  INLINE explicit ConfigVariableFilename(const std::string &name);
   INLINE ConfigVariableFilename(const std::string &name, const Filename &default_value,
                                 const std::string &description = std::string(), int flags = 0);
 
diff --git a/dtool/src/prc/configVariableInt.h b/dtool/src/prc/configVariableInt.h
index cd116557ed..2183032ce6 100644
--- a/dtool/src/prc/configVariableInt.h
+++ b/dtool/src/prc/configVariableInt.h
@@ -23,7 +23,7 @@
  */
 class EXPCL_DTOOL_PRC ConfigVariableInt : public ConfigVariable {
 PUBLISHED:
-  INLINE ConfigVariableInt(const std::string &name);
+  INLINE explicit ConfigVariableInt(const std::string &name);
   INLINE ConfigVariableInt(const std::string &name, int default_value,
                            const std::string &description = std::string(),
                            int flags = 0);
diff --git a/dtool/src/prc/configVariableInt64.h b/dtool/src/prc/configVariableInt64.h
index 7241219085..a85876ba1d 100644
--- a/dtool/src/prc/configVariableInt64.h
+++ b/dtool/src/prc/configVariableInt64.h
@@ -24,7 +24,7 @@
  */
 class EXPCL_DTOOL_PRC ConfigVariableInt64 : public ConfigVariable {
 PUBLISHED:
-  INLINE ConfigVariableInt64(const std::string &name);
+  INLINE explicit ConfigVariableInt64(const std::string &name);
   INLINE ConfigVariableInt64(const std::string &name, int64_t default_value,
                              const std::string &description = std::string(),
                              int flags = 0);
diff --git a/panda/src/downloader/urlSpec.h b/panda/src/downloader/urlSpec.h
index df5a7b9bb6..91a4e7a5bf 100644
--- a/panda/src/downloader/urlSpec.h
+++ b/panda/src/downloader/urlSpec.h
@@ -29,7 +29,7 @@ class EXPCL_PANDA_DOWNLOADER URLSpec {
 PUBLISHED:
   URLSpec();
   INLINE URLSpec(const std::string &url, bool server_name_expected = false);
-  URLSpec(const URLSpec &url, const Filename &path);
+  explicit URLSpec(const URLSpec &url, const Filename &path);
   INLINE void operator = (const std::string &url);
 
   INLINE bool operator == (const URLSpec &other) const;
diff --git a/panda/src/express/datagram.h b/panda/src/express/datagram.h
index e0590427f0..20821fc37e 100644
--- a/panda/src/express/datagram.h
+++ b/panda/src/express/datagram.h
@@ -38,7 +38,7 @@
 class EXPCL_PANDA_EXPRESS Datagram : public TypedObject {
 PUBLISHED:
   INLINE Datagram() = default;
-  INLINE Datagram(const void *data, size_t size);
+  INLINE explicit Datagram(const void *data, size_t size);
   INLINE explicit Datagram(vector_uchar data);
   Datagram(const Datagram &copy) = default;
   Datagram(Datagram &&from) noexcept = default;
diff --git a/panda/src/gobj/texture.cxx b/panda/src/gobj/texture.cxx
index cb7d06f7cb..05dee83ab7 100644
--- a/panda/src/gobj/texture.cxx
+++ b/panda/src/gobj/texture.cxx
@@ -10455,9 +10455,9 @@ make_this_from_bam(const FactoryParams &params) {
         // If texture filename was given relative to the bam filename, expand
         // it now.
         Filename bam_dir = manager->get_filename().get_dirname();
-        vfs->resolve_filename(filename, bam_dir);
+        vfs->resolve_filename(filename, DSearchPath(bam_dir));
         if (!alpha_filename.empty()) {
-          vfs->resolve_filename(alpha_filename, bam_dir);
+          vfs->resolve_filename(alpha_filename, DSearchPath(bam_dir));
         }
       }
 
diff --git a/panda/src/linmath/lvecBase3_src.h b/panda/src/linmath/lvecBase3_src.h
index 8594f1b921..567adae9c9 100644
--- a/panda/src/linmath/lvecBase3_src.h
+++ b/panda/src/linmath/lvecBase3_src.h
@@ -33,7 +33,7 @@ PUBLISHED:
   INLINE_LINMATH FLOATNAME(LVecBase3)() = default;
   INLINE_LINMATH FLOATNAME(LVecBase3)(FLOATTYPE fill_value);
   INLINE_LINMATH FLOATNAME(LVecBase3)(FLOATTYPE x, FLOATTYPE y, FLOATTYPE z);
-  INLINE_LINMATH FLOATNAME(LVecBase3)(const FLOATNAME(LVecBase2) &copy, FLOATTYPE z);
+  INLINE_LINMATH explicit FLOATNAME(LVecBase3)(const FLOATNAME(LVecBase2) &copy, FLOATTYPE z);
   ALLOC_DELETED_CHAIN(FLOATNAME(LVecBase3));
 
 #ifdef CPPPARSER
diff --git a/panda/src/linmath/lvecBase4_src.h b/panda/src/linmath/lvecBase4_src.h
index 8e9fe9a81d..aed77a9470 100644
--- a/panda/src/linmath/lvecBase4_src.h
+++ b/panda/src/linmath/lvecBase4_src.h
@@ -40,7 +40,7 @@ PUBLISHED:
   INLINE_LINMATH FLOATNAME(LVecBase4)(FLOATTYPE fill_value);
   INLINE_LINMATH FLOATNAME(LVecBase4)(FLOATTYPE x, FLOATTYPE y, FLOATTYPE z, FLOATTYPE w);
   INLINE_LINMATH FLOATNAME(LVecBase4)(const FLOATNAME(UnalignedLVecBase4) &copy);
-  INLINE_LINMATH FLOATNAME(LVecBase4)(const FLOATNAME(LVecBase3) &copy, FLOATTYPE w);
+  INLINE_LINMATH explicit FLOATNAME(LVecBase4)(const FLOATNAME(LVecBase3) &copy, FLOATTYPE w);
   INLINE_LINMATH FLOATNAME(LVecBase4)(const FLOATNAME(LPoint3) &point);
   INLINE_LINMATH FLOATNAME(LVecBase4)(const FLOATNAME(LVector3) &vector);
   ALLOC_DELETED_CHAIN(FLOATNAME(LVecBase4));
diff --git a/panda/src/pnmimage/pnmimage_base.h b/panda/src/pnmimage/pnmimage_base.h
index aa5474e82a..f3db5ff226 100644
--- a/panda/src/pnmimage/pnmimage_base.h
+++ b/panda/src/pnmimage/pnmimage_base.h
@@ -41,7 +41,7 @@ typedef unsigned char gray;
 struct pixel {
 PUBLISHED:
   pixel() = default;
-  pixel(gray fill) : r(fill), g(fill), b(fill) { }
+  explicit pixel(gray fill) : r(fill), g(fill), b(fill) { }
   pixel(gray r, gray g, gray b) : r(r), g(g), b(b) { }
 
   gray operator [](int i) const { nassertr(i >= 0 && i < 3, 0); return *(&r + i); }
diff --git a/panda/src/putil/buttonHandle.h b/panda/src/putil/buttonHandle.h
index 6e9dd9a40f..6c47a7df2d 100644
--- a/panda/src/putil/buttonHandle.h
+++ b/panda/src/putil/buttonHandle.h
@@ -30,7 +30,7 @@ PUBLISHED:
   // its value, it  might happen after the value had already been set
   // previously by another static initializer!
   INLINE ButtonHandle() = default;
-  constexpr ButtonHandle(int index);
+  explicit constexpr ButtonHandle(int index);
   ButtonHandle(const std::string &name);
 
 PUBLISHED:
diff --git a/panda/src/putil/loaderOptions.h b/panda/src/putil/loaderOptions.h
index 36ac016aef..826f5d072e 100644
--- a/panda/src/putil/loaderOptions.h
+++ b/panda/src/putil/loaderOptions.h
@@ -49,8 +49,8 @@ PUBLISHED:
     TF_no_filters        = 0x0400,  // disallow using texture pool filters
   };
 
-  LoaderOptions(int flags = LF_search | LF_report_errors);
-  constexpr LoaderOptions(int flags, int texture_flags);
+  explicit LoaderOptions(int flags = LF_search | LF_report_errors);
+  explicit constexpr LoaderOptions(int flags, int texture_flags);
 
   INLINE void set_flags(int flags);
   INLINE int get_flags() const;